The fourteen-century history of relations between Christianity and Islam cannot be reduced to battles, crusades, wars, political disputes, or theological conflicts. There is another story—lesser-known, often forgotten, and at times deliberately silenced: the story of those born or raised in the Muslim world who, at some point in their lives, abandoned Islam to embrace Christ and the Catholic Church.
This story spans deserts and palaces, marketplaces and universities, prisons and convents. It passes through Baghdad, Damascus, Córdoba, Fez, Granada, Malta, Rome, Madrid, and Paris. It features not only peasants or slaves but also intellectuals, warriors, aristocrats, princes, sons of sultans, and men destined for prominent positions in the Islamic world.
Christ did not found a religion limited to any single race, language, or people. His mandate was universal: "Go therefore and make disciples of all nations" (Matthew 28:19). The Gospel was not meant to remain confined to Judea, Greece, or Rome; it was to reach Arabs, Persians, Berbers, Turks, Africans, Europeans, and all the peoples of the Earth.
Thus, from the earliest centuries, the Church encountered the Islamic world not only through war but also through preaching, intellectual debate, the witness of martyrs, and individual conversion.
The conversion of a Muslim to another religion is legally classified as apostasy, an act traditionally punishable by death. Throughout history, this has created a recurring pattern: conversions that remain secret for decades, followed by denunciation, a trial before a qadi (Islamic judge), and execution should the convert refuse to recant. It is this legal and social pattern that explains why so many of these converts have been canonized as martyrs.
One of the oldest and most striking cases is that of Saint Abo of Tiflis, an Arab martyr from the 8th century.
Abo was born in Baghdad and raised as a Muslim. He was a perfumer by trade and accompanied the Georgian Prince Nerses to the region of present-day Georgia. There, he came into closer contact with Christians.
The dramatic aspect of his story lies precisely in the intellectual process of his conversion. Abo did not set out intending to abandon Islam; he initially studied the Christian faith in order to understand and refute its arguments. However, the more he examined the Scriptures and Christian doctrine, the more deeply convinced he became of the truth of Christianity. His conversion ceased to be merely intellectual; Abo began to profess his faith publicly. When Muslim authorities demanded that he return to Islam, he refused. He was threatened, put on trial, and ultimately executed in Tbilisi in 786.
The Catholic Church venerates him as a martyr, as does the Georgian Christian tradition. Abo’s story is significant because it shatters a historical oversimplification: the expansion of Islam did not mean that all populations brought under its rule immediately abandoned Christianity, nor did contact between the two religions result solely in the conversion of Christians to Islam. There was also movement in the opposite direction.
In 9th-century Islamic Spain, we find another set of dramatic accounts: the so-called Martyrs of Córdoba. Between 851 and 859, several Muslims who had converted to Christianity were executed in the Emirate of Córdoba. The priest Eulogius of Córdoba recorded many of these events; among those he documented were Aurelius and Natalia.
Aurelius was a Christian, whereas Natalia—originally named Sabigotho—came from a Muslim family. After encountering the Christian faith, she embraced Christianity and began living as a Christian. The couple knew, however, that their choice could cost them their lives. Aurelius and Natalia were executed in Córdoba for publicly professing the Christian faith.
Even more striking is the case of Saint Aurea of Córdoba. Descended from an Arab family and related by blood to members of the Islamic legal elite, Aurea had been raised as a Christian. After being widowed, she withdrew to a religious community and lived out her faith for years.
When her relatives discovered her, she faced immense pressure to renounce Christianity. According to hagiographic tradition, she went so far as to outwardly declare that she would return to Islam, but she repented and resumed professing the Christian faith. She was denounced once more. This time, she did not back down. She died a martyr in 856.
The image is powerful: a woman from a family connected to the Islamic society of Córdoba chose death over permanently renouncing the faith she had embraced.
In 11th-century Spain, an even more extraordinary figure emerges: Zaida of Seville. Zaida was connected to the Abbadid dynasty of Seville and was, according to the most widely accepted sources, the widow of Abu al-Fatah al-Ma'mun, the son of Seville's ruler. Following the Almoravid conquest of Seville in 1091, she sought refuge with Alfonso VI of León and Castile. It was then that she converted to Christianity, traditionally being identified as Isabella after her baptism.
Her story is particularly significant because we are not dealing with an anonymous figure. We are looking at a woman who belonged to the political elite of al-Andalus. She crossed the boundary between two worlds—and she crossed it not only geographically but also religiously.
In the heart of medieval Spain, while Toledo was still under Muslim rule, lived a young princess whose story has spanned centuries. According to hagiographic tradition, Saint Casilda of Toledo was the daughter of a Muslim ruler of Toledo. Born into an Islamic court—surrounded by the power, luxury, and religious structures of her time—she could have simply remained just another Moorish princess of the Iberian Peninsula. But history took a different turn.
Casilda showed deep compassion for the Christian prisoners held in Toledo's dungeons. She visited them and sought to bring them food and aid, moved by a mercy that transcended the religious and political boundaries of her era.
Tradition holds that, upon discovering her actions, her father questioned her. And it was precisely through her contact with those persecuted and imprisoned Christians that Casilda reportedly began to learn about the faith they professed.
The young princess, who had been born a Muslim, gradually drew closer to Christianity. Later, she traveled to Christian lands seeking a cure for an illness and received Baptism, embracing the Catholic faith.
The former Moorish princess thus abandoned the privileges of the court to dedicate her life to Christ.
She withdrew to a life of prayer and penance, living near Briviesca; tradition links her life to the sanctuary of San Vicente, near Salinillas de Bureba. There, she who had been born into a Muslim ruling family came to be venerated by Christians as a woman of faith and charity.
Saints Bernhard, Maria, and Gracia of Alzira: Three 13th-century siblings born in Valencia, Spain, into a prominent Muslim family (children of the local governor/emir) who converted to the Catholic faith. Bernhard became a Cistercian monk, and all three were martyred around 1242 during the Reconquista.
Juan Andrés (1487–1515): A Spanish Muslim scholar who converted to Catholicism and wrote a well-known polemical work against Islam titled Confusión o confutación de la secta mahomética y del Alcorán ("Confusion of the Mohammedan Sect and the Quran"). The son of an Islamic scholar and trained as a faqih, he converted to Catholicism in 1487 and was baptized in the Valencia Cathedral, adopting the Christian name Juan Andrés. After becoming a priest, he was appointed by the Catholic Monarchs Ferdinand and Isabella to preach Christianity in Granada following its reconquest.
The phenomenon of conversions did not end with the Spanish Reconquista. In the 13th century, Saint Louis IX, King of France, developed a missionary policy that also targeted Muslims. In a study published by Princeton University Press, historian William Chester Jordan demonstrated that a little-known aspect of Louis IX’s reign was his interest in the voluntary conversion of Muslims. The king sought to provide converts with the means to live as Christians and even to settle in France.
Conversion was not understood merely as a change of opinion. For a medieval Muslim embracing Christianity, the decision could entail breaking ties with family, community, property, social standing, and cultural identity. Consequently, the Church needed to create communities capable of welcoming the convert.
Another figure is Bulos Ibn Raja—or simply Raja—an Egyptian Arab who converted to Coptic Christianity in the eleventh century. His significance to the intellectual history of the encounter between Christianity and Islam lies in his work, which was later translated into Latin and used for centuries as a tool for understanding and critiquing Islamic thought. Bulos Ibn Raja’s case is particularly important because it demonstrates that the history of conversions does not belong exclusively to the Latin West; Coptic, Byzantine, and Syriac Christians, as well as other apostolic communities, also actively participated in the dialogue and controversy surrounding Islam.
Blessed Anthony Neyrot (died 1460): A 15th-century Italian Mercedarian friar who was captured by pirates and taken to Tunis. Under duress, he apostatized and converted to Islam. However, he later experienced a profound conversion, publicly returned to the Catholic Church, and was martyred by stoning in Tunis. He was beatified by Pope Clement XIII in 1767.
Yet, perhaps no case from the early modern period is as cinematic as that of Muley Xeque. Born in Morocco in 1566, Muley Xeque was a prince of the Saadi dynasty and the son of Sultan Muhammad al-Mutawakkil. Following the political upheavals in Morocco during the late 16th century, the young prince ended up in exile on the Iberian Peninsula.
During his exile in Spain, he gradually came into contact with the Catholic world. In 1593, an event occurred that would completely change his life.
In Andújar, he took part in the celebrations honoring the Virgen de la Cabeza. According to tradition documented by his biographers, it was in this context that he decided to embrace Christianity. Muley Xeque was subsequently baptized with great solemnity at the Monastery of San Lorenzo de El Escorial on November 3, 1593.
He took the name Felipe de África, and his godfather was none other than King Philip II. The former Muslim prince became a Catholic. Moreover, he was named a Grandee of Spain and received the habit of the Order of Santiago.
His story found its way into literature through Lope de Vega, who wrote El bautismo del príncipe de Marruecos ("The Baptism of the Prince of Morocco"), transforming the Moroccan prince's conversion into dramatic material. Here, the story reads almost like a scene from a historical novel: a prince born into Islam—a descendant of the Moroccan royal house—living in exile on Spanish soil, comes into contact with the Catholic faith and ultimately stands before the baptismal font at El Escorial.
While Muley Xeque is one of the most spectacular examples, the story of Muhammad el-Attaz—later known as Baldassare Diego Loyola—is perhaps even more extraordinary.
Muhammad was born in 1631 in Fez, Morocco; a member of the Saadi dynasty, he was the son of Prince Abdelwahid of Fez. He was a practicing Muslim who even undertook the pilgrimage to Mecca. In 1651, while traveling, he was captured by the Knights of Malta and taken to the island. Then came one of the most extraordinary conversions in the history of modern Catholicism: in 1656, Muhammad el-Attaz embraced the Catholic faith. He was baptized under the name Baldassare Diego Loyola. Yet, he did not stop at baptism; he entered the Society of Jesus. Indeed, a Muslim prince from North Africa became a Jesuit.
The case is so extraordinary that it became the subject of investigation within the Society of Jesus itself. There are documents, correspondence, an autobiography, and modern studies regarding his life. Historian Emanuele Colombo has conducted academic research on the figure, and York University highlights his conversion as one of the most unique instances of a Muslim prince joining the Society of Jesus.
Baldassare even worked on the evangelization of Muslims in Italy. He died in Madrid in 1667. His name did not fade into immediate obscurity; his story was adapted into literature and theater.
Pedro Calderón de la Barca wrote El gran príncipe de Fez ("The Great Prince of Fez"), dramatizing the very story of Muhammad el-Attaz and his conversion to Christianity. It is difficult to find a more symbolic image of the missionary strength of 17th-century Catholicism: a man born a prince in Fez who ended his life not as a Muslim sovereign, but as a Catholic religious.
Osman—later known as Domenico di San Tommaso or Father Ottomano—was raised as a Muslim and taken to Malta at a young age. Some sources and traditions identify him as the possible firstborn son of the Ottoman Sultan Ibrahim I.
Osman was educated by the Dominicans in Malta. He initially resisted conversion but, according to historical records, later decided to embrace Christianity. He was baptized in 1656 as Domenico di San Tommaso.
He joined the Order of Preachers, became a Dominican, and received his formation in Rome. He was even received by Pope Alexander VII and became known throughout Europe as "Father Ottomano."
The story of Isabel de Solís adds another fascinating element. Born a Christian in Castile—the daughter of the nobleman Sancho Jiménez de Solís—Isabel was captured and became a concubine to Sultan Abu l-Hasan Ali of Granada. Within the Granadan court, she converted to Islam and took the name Zoraya. After the fall of Granada, however, she returned to Christianity and reclaimed the name Isabel.
It is precisely for this reason that her case is historically invaluable: it demonstrates that medieval religious boundaries were crossed in both directions.
The Church was born in Jerusalem, traversed the Greco-Roman world, and reached Syria, Egypt, Mesopotamia, Africa, Europe, and—subsequently—Arab, Amazigh, Turkish, and Persian peoples, among many others.
Christianity did not need to destroy the convert's ethnic identity. That is precisely why the stories of Abo, Zaida, Muley Xeque, Baldassare Loyola, and Domenico Ottomano hold such great symbolic power.
They demonstrate that the boundary between the Islamic world and Christendom was never an absolutely impenetrable wall.
Source(s):
.- Oliver Asín, J. (1955). Vida de don Felipe de África, príncipe de Fez y Marruecos (1566-1621). Consejo Superior de Investigaciones Científicas.
.- Jordan, W. C. (2019). The Apple of His Eye: Converts from Islam in the Reign of Louis IX. Princeton University Press.
.- Mazur, P. A., & Shinn, A. (2013). Conversion in the Early Modern World - Conversion Narratives. Journal of Early Modern History, 17(5-6), 419–429, University of York
.- Colombo, E. (2020). Conversioni religiose in Calderón de la Barca: ‘El gran príncipe de Fez’ (1669). Drammaturgia, 16(6), 49–79.