Transcending Boundaries: A Comparative Analysis of Islamic and Christian Mysticism

Abstract

This study offers a comparative exploration of the mystical lives of Rābiʿa al-ʿAdawiyya and Catherine of Genoa, representing Islamic and Christian traditions, respectively. Moving beyond polarized approaches that either universalize or isolate mystical experience, it adopts a balanced framework to examine shared themes such as divine love, detachment, self-annihilation, and union with the Divine. Through biographical and thematic analysis, the paper highlights both convergence and divergence in their spiritual paths, proposing their legacies as models for interfaith dialogue, mutual understanding, and spiritual solidarity in a pluralistic world.

Keywords

Islam, Christianity, Mysticism, Interreligious Friendship

Introduction

In an era marked by deepening religious polarization and rising sectarian tensions, the call for authentic interreligious understanding has never been more urgent. While doctrinal differences often dominate public perceptions of Christianity and Islam, beneath these differences lies a rich reservoir of shared spiritual insight—particularly within the mystical traditions of both faiths. This study aims to uncover some of these resonances by examining the lives and teachings of two exemplary mystics: Rābiʿa al-ʿAdawiyya of Basra and Catherine of Genoa. Through a comparative exploration of their spiritual experiences and theological emphases, the paper proposes a framework for Muslim-Christian dialogue grounded not in abstract theological compromise, but in a shared longing for divine love and transformation.

The motivation behind this inquiry is both personal and theological. The author’s experience with religiously motivated violence in Nigeria, where a classmate was killed simply for belonging to a different religious group, highlighted the destructive power of misunderstanding and fear. It also revealed how religious identities, when weaponized, can fuel exclusion rather than healing. Against this backdrop, Said Nursi (d. 1960), a Muslim thinker from Turkey, identified ignorance, poverty, and disunity as the fundamental enemies of humanity. Building upon this vision, Fethullah Gülen (d. 2024) led a global civic movement aimed at addressing these challenges in practical terms—through the establishment of educational institutions, humanitarian aid organizations, and interfaith dialogue initiatives. Together, their legacy presents an alternative paradigm in which faith traditions are not threats to social cohesion but essential contributors to the common good when rightly understood and practiced.

This vision finds a powerful echo in the Catholic Church’s transformative shift at the Second Vatican Council (1962–1965). Documents such as Nostra Aetate, Lumen Gentium, and Ad Gentes emphasize the presence of divine truth beyond the boundaries of the Church and affirm the dignity and spiritual longing of all peoples. Nostra Aetate, in particular, describes other religions not as rivals, but as participants in the universal human search for meaning and salvation. Pope Benedict XVI even described the document as the “Magna Carta” of Catholic-Muslim relations. These conciliar texts represent a significant development in interfaith thinking, moving from exclusivism toward a theology of relational openness.

Yet, while such theological documents establish the legitimacy of interfaith engagement, they often remain theoretical or institutional. In contrast, the mystical lives of figures like Rābiʿa and Catherine offer lived models of what it means to relate to the divine across traditions—models that transcend theological abstractions and invite dialogue at the level of experience, humility, and love. This approach is particularly relevant today, as interreligious friendship increasingly depends not on agreement about doctrine but on shared values and mutual recognition of spiritual depth.

Mysticism, in this context, provides a powerful alternative to polemical theology. Unlike debates that focus on apologetics and confessional boundaries, mystical traditions emphasize personal transformation, the inner journey toward God, and the language of divine intimacy. Both Rābiʿa and Catherine exemplify this orientation. Rābiʿa, an 8th-century Sufi woman from Basra, is often regarded as a foundational figure in Islamic spirituality, known for her uncompromising emphasis on disinterested love (maḥabba) for God. Catherine of Genoa, a 15th-century Christian mystic, similarly articulated a vision of divine love that burns away the self in a purifying fire of grace. Despite their different historical and theological contexts, both mystics point to a spiritual path rooted in surrender, purification, and the overwhelming presence of divine love.

By drawing on their writings and historical portrayals, this study seeks to uncover common themes that can inform contemporary efforts in Muslim-Christian engagement. Rather than glossing over doctrinal differences, the paper embraces the distinctiveness of each tradition while exploring how their mystical insights can open new avenues for mutual understanding and shared witness in a fractured world. It argues that spiritual experience—especially when articulated in language shaped by love, self-effacement, and divine union—offers a fertile ground for reimagining interfaith relations not as compromise, but as mutual enrichment.

The structure of the paper follows a comparative methodology, first presenting the lives and contexts of Rābiʿa and Catherine, then analyzing core elements of their mystical thought—especially around themes of divine love, suffering, selfhood, and union. Finally, the study draws broader implications for interreligious dialogue, proposing mysticism as a trans-confessional space for spiritual solidarity.

In doing so, the paper hopes to contribute to a growing body of scholarship that sees mysticism not merely as a private religious phenomenon, but as a bridge across traditions—one that can lead to deeper compassion, collaboration, and peace among those who seek the face of God.

A Synopsis: Mysticism and Mystical Experiences

The study of mysticism has long fascinated scholars from diverse fields, yielding a range of definitions and interpretations. It is a common phenomenon in religion, yet its exact meaning remains debated among experts. Ralph Hood notes that many social scientists compare mysticism to suicide in terms of research difficulty; both are rare and hard to identify before they happen, making them elusive subjects for empirical study. (McNamara 2006, vol. 1, 124). Wayne Teasdale characterizes the mystic as someone who has attained profound inner integration and spiritual freedom, such that all dimensions of experience are embraced as part of a unified whole. This integration fosters openness toward diverse perspectives rather than resistance to them (Teasdale 1999, 232). William Ralph Inge defines mysticism as “the attempt to realize, in thought and feeling, the immanence of the temporal in the eternal, and the eternal in the temporal” (Inge 1899, 5). In contrast, Bernard McGinn describes mysticism as “an attempt to express a direct consciousness of the presence of God” (McGinn 1991, xvi).

Evelyn Underhill offers a broader definition, describing mysticism as “the expression of the innate tendency of the human spirit toward complete harmony with a transcendental order, regardless of the theological formula under which that order is understood” (Underhill 1961, xiv). In her view, mysticism is rooted in human spiritual orientation rather than dogmatic or institutional formulations.

Although mystical experiences are frequently associated with religious contexts, research has demonstrated that individuals who do not identify with any religious tradition- and who may not even consider themselves spiritual- can also report such experiences (Bledow 2022, 2). This raises the question of whether mysticism is intrinsically religious or whether it can transcend religious boundaries altogether.

Underhill further suggests that the mystic is one who has directly encountered the divine and has come to “realize God as an abiding Fact, a living Presence, and Love,” resulting in a radical transformation of the person’s entire existence (Underhill 1964, 12). However, some scholars have critiqued this definition as overly narrow, noting that mystical experience encompasses a variety of forms and cannot be confined to a single typology.

Sebastian Gäb identifies four general features commonly associated with mystical experience. First, mysticism is typically unitive, involving a sense of oneness with God, the universe, or the ground of being. This unitive state may manifest as a dissolution of the boundary between subject and object, or as a perception of the unity of all things. Second, mystical experiences are often noetic, conveying not just emotion but also a sense of insight or profound understanding. Third, some mystical experiences are contentless, devoid of specific visual or auditory perceptions of divine beings; others may include awareness of external objects or figures. Fourth, mystical experiences are marked by a profound emotional intensity, evoking states of bliss, awe, peace, and love (Gäb 2021, 3).

It is essential to acknowledge that these categories are not exhaustive, and mystical experiences vary significantly across different religious and cultural contexts. Some scholars argue that mysticism in monotheistic traditions exhibits cross-religious similarities, a perspective sometimes referred to as the common core thesis (Dupré 2012). Hamid Hussain supports this view, acknowledging that while each monotheistic tradition possesses its own unique mystical frameworks, there is evidence of mutual influence across Judaism, Christianity, and Islam. These shared elements include common prophetic figures, overlapping narratives, and similar spiritual aims found in their respective sacred texts (Hussain 2023).

Having established key definitions and categories relevant to the study of mysticism, the following section turns to the biographical backgrounds and mystical experiences of Rābiʿa al-ʿAdawiyya and Catherine of Genoa. While this thesis engages with and builds upon existing scholarship, it seeks to offer a distinctive contribution by employing a comparative theological framework to examine the mystical experiences of these two significant female figures, Rābiʿa from the Islamic tradition and Catherine from the Christian West. Through an exploration of their lives and spiritual journeys, this study aims to illuminate how each tradition uniquely articulates the path of mystical transformation, while also contributing to a broader, more integrative understanding of interreligious mysticism.

The Biographical Backgrounds and Mystical Experiences of Rābiʿa al-ʿAdawiyya and Catherine of Genoa

Catherine of Genoa

Catherine of Genoa (1447–1510), born Caterina Fieschi, was the youngest child of Giacopo Fieschi and Francesca di Negro, members of a distinguished noble family in Genoa, Italy (von Hügel 1927, vol. 1, 96–98). From an early age, Catherine demonstrated a deep devotion to prayer and penance, reportedly spending her nights in ascetic practices such as sleeping on bare wooden floors. Despite her noble status, she expressed a pronounced distaste for wealth and privilege. At the age of twelve, Catherine experienced a profound spiritual communion that intensified her desire for a life of religious dedication. She sought entrance into a convent by the age of thirteen, but her request was denied due to her youth. Following the death of her father, customary Genoese inheritance practices conferred authority and property to her eldest brother, who arranged her marriage to Giuliano Adorno—a union she entered reluctantly but with obedience and trust in divine providence (von Hügel 1927, vol. 1, 96).

Catherine’s early married life was marked by suffering, as Giuliano’s irreligiosity clashed with her spiritual aspirations. This dissonance led her into a period of existential distress. Although she pursued various activities in search of solace, none brought her peace. In a moment of desperation, on the eve of the feast of St. Benedict, she prayed fervently for divine intervention, asking for a period of physical affliction as a means of spiritual purification (von Hügel 1927, vol. 1, 104).

A pivotal moment occurred when her sister, Limbania, a nun, persuaded her to attend confession. Although initially hesitant, Catherine’s confession proved to be transformative. She later described receiving a dual revelation: an overwhelming awareness of God’s love and a piercing recognition of her own sinfulness. This experience was so intense that she reportedly lost consciousness during the sacrament of penance (von Hügel 1927, vol. 1, 116). Following this mystical encounter, Catherine underwent what she described as a complete spiritual purification. She spoke of being illuminated by divine light and wounded by love for God. This marked the beginning of a life of contemplative solitude, characterized by ecstatic prayer and radical detachment. As Don Cattaneo Marabotto notes, her subsequent writings reflect a soul consumed by divine love, yearning only for total union with God (Marabotto 1989).

Catherine’s mystical life was accompanied by acts of profound charity. After the death of her husband, who had converted and embraced a life of chastity before his passing, Catherine dedicated herself to caring for the sick and the poor. Benedict J. Groeschel recounts one of her mystical visions, in which she beheld Christ bearing the cross, bloodied and broken, yet motivated by pure love —an image that solidified her path of penitential devotion (Groeschel 1979, 38–42). Catherine’s spiritual legacy endures through her mystical writings and her reputation for sanctity. She was beatified by Pope Clement X in 1675 and canonized by Pope Clement XII in 1737 (Groeschel 1979).

Rābiʿa al-Adawiyya

Rābiʿa was a Sufi Muslim mystic. She was born around 717 A.D. in Basra, Iraq, to a low-income family. Legend has it that Rābiʿa s parents died while she was very young, and her siblings were forcefully removed from her at a tender age. As an orphan, Rābiʿa was kidnapped and sold into slavery. In her servitude, she served her master diligently day and night. So grievous was her suffering that she looked forward to a day when she would be freed (Smith 1984, 1)

During her intense suffering, one day Rābiʿa heard a voice that she believed was God’s voice saying, “Grieve not, for on the day of resurrection, thy rank shall be such that those nearest to God in heaven shall envy thee.” Strengthened by these words, Rābiʿa intensified her spiritual exercises, fasting during the day and spending her nights in prayer. Rābiʿa understood prayer not as mere intercession for herself or others but as a union with God. Thus, prayer is a complete devotion to the divine Love. For Rābiʿa, God must be loved for His sake only and not for anything else (Smith 1984).

Rābiʿa was a celibate, and the adoption of celibacy, too, was quite alien to orthodox Muslims. At a time when marriage was valued and esteemed by orthodox Muslims, Rābiʿa stood as a sign of contradiction. She rejected all her marriage proposals, stating that marriage is for those who exist only for the pleasures of this world. In her own words: “For me, that is not so, since I have ceased to exist, and I have passed out of self. My life is in my Lord, and I am altogether His” (Smith 1984). Marriage in Islam is not only a choice but also a responsibility. Surprisingly, no known work criticizes Rābiʿa for her decision to remain celibate. In defending Rābiʿa’s choice of celibacy, Farid al-Din Attar states that if he is asked, “Why have you included Rābiʿa in the rank of men?’ my answer is that the prophet himself said, ‘God does not regard your outward forms …’ Moreover, if it is permissible to derive two-thirds of our religion from A’esha, surely it is permissible to take religious instruction from a handmaid of A’esha” (Aṭṭār 1984, 40). Through this quotation, Aṭṭār seems to argue that gender does not matter. God’s choice to use people as His chosen instrument is not limited by gender.

Another virtue that stood out for Rābiʿa was her life of prayer and the practice of poverty. Her prayer life developed through the path of poverty and self-denial. This was evident in her extreme ascetic life; she denounced everything related to the world in order to commit fully to the things of the divine. Legend has it that Rābiʿa had several opportunities to become rich but chose not to. For example, a story was told about how some visitors brought Rābiʿa gifts, but she wouldn’t accept such gifts because she thought God would take care of her needs. Rābiʿa is the epitome of what it means to rely entirely on divine providence, as expressed in her own words, “shall God who provides for those who revile him, not provide for those who love Him? He does not refuse sustenance to one who speaks unworthily of Him. How should he refuse it to one whose soul is overflowing with love toward Him?” (Smith 1930). Rābiʿa thus continued in her demanding quest for a complete union with the divine.

Rābiʿa lived with the passion and zeal of a true lover who puts God ahead of all things. For Rābiʿa, commitment to God meant turning away from sin and all material attractions. By so doing, one is prepared to empty oneself completely of worldly affairs for the sake of the divine. According to John O’Brien, the most famous prayer that shaped Rābiʿa’s attitude of disinterested love for the divine is expressed as follows: “If I worship You from fear of Hell, burn me in Hell, and if I worship You from the hope of Heaven, exclude me thence, but if I worship You for Your own sake, then withhold not from me Your eternal beauty” (O’Brien 2010, 84). This quote exemplifies Rābiʿa’s selfless devotion to God. In other words, Rābiʿa seeks to love God without any expectation of reward.

In the early centuries of Sufism, Margaret Smith points out how Rābiʿa’s concept of love transformed Sufis’ fear of God into pure, selfless love. The love of God came to be understood as pure love, with no conflicts with beliefs or orthodox interpretations. According to O’Brien, this kind of love excludes any external association. It is a total and disinterested love which moves beyond any desire for recompense. It is a pure love rooted in the soul’s thirst for God (O’Brien 2010, 84).

Rābiʿa believed that the way to God must be sought through love, which made her the first among the Sufis to teach the doctrine of the disinterested love of God. Legend again has it that Rābiʿa was seen taking fire in one hand and water in the other and running with great speed. When she was asked the reason for her action, she said: “I am going to set fire to Paradise and quench the fires of Hell so that men may worship God for his own glory alone” (O’Brien 2010, 91). By this statement, Rābiʿa implied again that God must be sought not because of the joy of heaven or the fear of hell but for the sake of God himself. Rābiʿa was over eighty years old when she died in AD. 801 (O’Brien 2010, 91).

Common Themes in the Mystical Experiences of Rābiʿa and Catherine

The Love of God as Pure Love

One of the striking commonalities between Catherine and Rābiʿa is the notion of pure love. It is worth noting that, despite the differences in their religious beliefs, these two mystics share a salient concept about the love of God. Both understand the relationship with God as pure love. They believed that love is the foundation and purpose of all relationships. Thus, God must be approached and worshiped for love alone. Catherine puts it more succinctly, saying the following:

Before God created man, love was pure and simple, free from all taint of self-interest and needing no restraint. And in creating man, God was moved by no other cause except his pure love. In all that he did for him, he had no other motive or object. And as his love allows nothing to prevent it from doing all possible good to its beloved, and attends to nothing which is not necessary to that end, so the love of man should return to God all that it receives from him; and then, having no respect for anything but love, it will fear nothing, because it never seeks its advantage (Hügel and Von 1923).

A close examination of the lives of Rābiʿa and Catherine reveals that all their actions were driven by pure love. We see this example in their fierce love of God, which was made concrete through the service of others. Both mystics discovered that the true wealth in life lies in fervent love for the divine, demonstrated by serving others. Furthermore, these two souls were so driven by their love for God that no force could separate them. Here is how Catherine expressed it:

Genuine and pure love is such a force that it cannot be diverted from its object, nor can it see or feel anything else. Hence it is a useless toil to try to make such creatures employ themselves in the things of this world, as regard to them they are as insensible as if there were dead. (Hügel and Von 1923)

Harvey D. Egan emphasized Catherine’s profound love for God, stating that God as pure love, incomprehensible love, is the salient feature of Catherine’s mysticism. He adds that the ray of burning love united Catherine so closely to God that nothing could separate her from Him (Egan 2012). Von Hugel supports Egan’s assertion that Catherine, infused with divine love at some point in her life, was able to contemplate the divine with ardent passion. Catherine lacks adequate words to explain her love relationship with the divine, saying:

It is impossible to describe this love in words or figures which, in comparison with the reality, seem entirely false. This only can only be understood, namely, that the human intellect is unable to comprehend it. And to him who seeks to know what it is that I know and feel, I can only reply that it transcends all utterance (Hügel and Von 1923).

Rābiʿa’s concept of divine love is akin to Catherine’s. Drawing from her Sufi background, Rābiʿa understands a relationship with God as pure love. The notion of disinterested love forms the core of her teaching. We see a reflection of the concept of disinterested love in her famous quote mentioned earlier:

If I worship Thee from fear of Hell,
Burn me in hell.
And if I worship Thee in the hope of paradise,
Exclude me thence,
But if I worship Thee for Thine own sake,
Then withhold not from me
Thine eternal beauty. (O’Brien 2010, 83)

Rābiʿa suggests that spirituality should extend beyond the traditional notion of paradise as a place of happiness or a reward for a devout life. Instead, she believes that God should be worshipped from a perspective of pure love. This love should overflow into one’s relationships with others, making them feel unconditionally loved. In a similar tone, William Ralph Inge states, “Love is not love when it asks for a reward (Inge 1899, 83).” Like Catherine, Rābiʿa argues that love, not fear, should be the basis of worshipping God. Rābiʿa thinks the two veils stopping people from approaching God with pure love are the fear of hell and the fear of losing heaven. If there were no hell or heaven, would people still worship God? The concept that God should be worshipped and loved purely for the sake of love is central to the mystical experiences of Rābiʿa and Catherine of Genoa. St. Francis Xavier is another saint who articulated a similar idea about the concept of pure love as the foundation for a relationship with God. Legend has it that Francis drew his inspiration from Rābiʿa’s thought when he composed the following:

O’ God, I love thee, I love thee
Not out of hope of heaven for me
Nor fearing not to love and be
In the everlasting burning…
Not for heaven’s sake, not to be
Out of hell by loving thee
Not for any gains I see
But just the way that thou didst me
I do love and I will love thee… (Fremantle 1977,  54)

Further, Theresa of Lisieux, one of the modern saints who is also known as The Little Flower, has a notion of pure love that resembles that of Rābiʿa and Catherine when she says: “My Jesus, Thou knowest I do not serve Thee for the sake of reward, but solely out of love and desire to win Thee souls” (Fremantle 1977, 54). Thus, the ultimate goal of these mystics is a complete love relationship with the divine. This leads us to our next discussion on self-denial and sin.

Self-Denial and a Deep Sense of Sin

Another point of symmetry between Rābiʿa and Catherine is their deep sense of sin. It is commonplace for mystics to continually soul-search for any sin that could cloud their vision of the divine. John of the Cross, one of the ascetical-mystical geniuses of the fifteenth century who was known for his life of austerity, asserts that mystics become conscious of sin or any stain on their soul because the closer they get to God the more illuminated they become, and the more illuminated they become, the more their sense of guilt heightens; consequently, imperfection becomes transparent. John of the Cross refers to the process by which one’s imperfection becomes transparent, where one stands naked before God, naked alone with the Alone as a “mirror for the beginner” (Fremantle 1977, 54). John explains that the moment of standing naked before God is not a time of judgment but a moment that also reveals God’s love and grace, which surpasses all sins (Muto and Muto 1994, 33).

Like Rābiʿa and John, every tidbit of Catherine’s actions reminds her of her imperfection before the divine. As previously noted, Catherine developed a sense of guilt from a very tender age, for her sin is unbearable, hurtful, and should be avoided. She once cried out, “Oh Lord, no more world, no more sin(Egan 2012).” One may conclude that the secret of Rābiʿa’s and Catherine’s repulsion for sin is the understanding that sin creates a gap between the beloved and the lover. This gap often causes excruciating pain that is hard to bear. Speaking of this effect, Egan states that “the more deeply one experiences God’s nearness, the more one awakens to one’s sinfulness and creaturely nothingness” (Egan 2012). Egan adds that the consciousness of sin as an obstacle is a stage in the mystical journey toward transforming the union between sin and grace. We see Rābiʿa’s repulsion of sin in her long hours of night prayers and penance when she says: “My sorrow is not for the things which make me grieve, but my sorrow is for the sins for which I do not grieve” (Smith 1984, 47). Both Rābiʿa and Catherine believe that sin is hurtful to the soul to the highest degree, not because it involves punishment in the hereafter, but because it is the cause of separation between the soul and God.

The Desire for Union with the Divine

At the heart of every mystic is the desire to be wholly united with the divine. Like Catherine, Rābiʿa believes she belongs so utterly to God that she cannot think of any other relationship except her relationship with the divine. This fact was evident in the number of times Rābiʿa refused to get married, stating: “My life is in my Lord, and I am altogether His. The marriage contract must be asked for from Him and not from me” (Smith 1984,  47). Unlike Rābiʿa, Catherine was married, but at a point before her husband’s death, both agreed to a chaste marriage; that is, even though they were legally married, they chose to remain celibate. Both Catherine and Rābiʿa understand perfection as a union with the divine, a union that is so profound that separation between the mystic and the divine would be impossible. According to Egan, most mystics think this union prefigures the beatific vision (Egan 2012).

Conclusion

In bringing together the mystical experiences and theological insights of Rābiʿa al-ʿAdawiyya and Catherine of Genoa, this study has attempted to underscore the profound resonance between Islamic and Christian traditions in their most intimate spiritual expressions. Despite the historical, doctrinal, and cultural differences between these two figures, they converge remarkably in their emphasis on divine love, self-effacement, and the interior transformation of the soul. Rābiʿa’s unrelenting devotion to God, expressed through radical notions of selfless love, finds a compelling echo in Catherine’s theology of purgative suffering and total abandonment to divine will. Together, they illustrate how mystical traditions within both Islam and Christianity transcend polemics and doctrinal boundaries to affirm the human capacity to experience the Divine directly and intensely. Their voices, though distant in geography and time, invite a renewed interfaith appreciation for the shared mystical heritage that continues to inspire seekers across religious divides. Such comparative studies can foster deeper dialogue and empathy in an increasingly fragmented world, where spiritual depth and mutual understanding are ever more essential.

Bibliography

1. Attar, Farid ud-Din. Tadhkirat al-Awliya. Translated by A. J. Arberry. London: Paul Lund, Humphries, 1966.
2. Bledow, Nona. 2022. “The Epistemic Value of Non-Religious Mystical Experiences.” Religions 13 (11): 1116. https://doi.org/10.3390/rel13111116. (accessed on 12 January 2024).
3. Bowie, Fiona. The Anthropology of Religion: An Introduction. Malden: Blackwell Publishing, 2006.
4. Catherine of Genoa. Treatise on Purgatory. Translated by Charlotte B. Gardner. Rockford: Tan Books, 1973.
5. Chittick, William C. Sufism: A Beginner’s Guide. Oxford: Oneworld Publications, 2000.
6. Dupré, Louis in. 2012. Routledge Companion to Philosophy of Religion Ed. by Meister, Chad and Copan, Paul. London: Routledge.
7. Egan, Harvey D. 2012. “In Purgatory We Shall All Be Mystics.” Theological Studies 73 (4): 870 89.
8. Ernst, Carl W. Sufism: An Introduction to the Mystical Tradition of Islam. Boston: Shambhala, 1997.
9. Fremantle, Anne Jackson. 1977. Woman’s Way to God. New York: St. Martin’s Press.
10. Gäb, Sebastian. 2021. “Mysticism without Concepts.” International Journal for Philosophy of Religion 90:1–14. https://doi.org/10.1007/s11153-021-09799-7. (accessed on 22 February 2024).
11. Groeschel, Benedict J. 1979. Introduction, Catherine of Genoa: Purgation and Purgatory. The Spiritual Dialogue, Trans. Serge Hughes, Classics of Western Spirituality. New York: Paulist.
12. Hussain, Hamid. 2023. “Abrahamic Mysticism: A Shared Heritage.” Science and Nonduality. https://scienceandnonduality.com/article/abrahamic-mysticism-a-shared-heritage/#:~:text=The%20influence%20of%20mysticism%20within,trends%20of%20all%20three%20religions. (accessed on 12 July 2024).
13. Inge, William Ralph. 1899. Christian Mystics. London: Methuen,.
14. ———. 1956. Christian Mysticism. 7th ed. New York: Meridan Books.
15. Karamustafa, Ahmet T. Sufism: The Formative Period. Edinburgh: Edinburgh University Press, 2007.
16. Marabotto, Don Cattaneo. 1989. The Spiritual Doctrine of St. Catherine of Genoa. Rockford, IL: Tan Books and Publishers.
17. McGinn, Bernard. 1991a. The Foundations of Mysticism: Origins to the Fifth Century. New York: Crossroad.
18. ———. 1991b. The Presence of God: A History of Western Christian Mysticism. New York: Crossroad.
19. McNamara, Patrick. 2006. The Common Core Thesis in the Study of Mysticism in Where God and Science Meet: How Brain and Evolutionary Studies Alter Our Understanding of Religions. Vol. 1. Westport, CT: Praeger Publishers.
20. Nasr, Seyyed Hossein. Three Muslim Sages: Avicenna, Suhrawardi, Ibn Arabi. Delmar, NY: Caravan Books, 1976.
21. Muto, Susan, and Susan Annette Muto. 1994. John of the Cross for Today: The Dark Night. Notre Dame, Indiana: Ave Maria Press.
22. O’Brien, John. 2010. “Rabi`a Al-`Adawiyya: Women Mystics and the Pure Love of God.” Milltown Studies.” Milltown Studies, 57 No. 2.
23. Smith, Margaret. 1930. “Rābi’a the Mystic.” Muslim World 20 (4): 337–43.
24. ———. 1984. Rābiʻa the Mystic & Her Fellow-Saints in Islām: Being the Life and Teachings of Rābiʻa Al-ʻAdawiyya Al-Qaysiyya of Baĩra Together with Some Account of the Place of the Women Saints in Islām. New York: Cambridge University Press.
25. Teasdale, Wayne. 1999. The Mystic Heart – Discovering a Universal Spirituality in the World’s Religions. Novato, California: New World Library. https://newworldlibrary.com/product/the-mystic-heart. (accessed on 2 January 2024).
26. Underhill, Evelyn. Mysticism: A Study in the Nature and Development of Spiritual Consciousness. New York: Dutton, 1911.
27. Von Hügel, Baron Friedrich. 1927. The Mystical Element of Religion, as Studied in Saint Catherine of Genoa and Her Friends, Volume. Vol. 1. London: J.M. Dent & Sons.
28. Waugh, Earle H. The Munshidin of Egypt: Their World and Their Song. Columbia: University of South Carolina Press, 1989.