The doctors of the church are saints recognized for their important contributions to theology and doctrine through their research, study, and writing. The term ‘doctor of the church’ does not mean they were academics or had earned doctorates, but rather that they were known as authoritative teachers of faith and morals. While the specific number of doctors can vary between denominations, the Catholic Church officially recognizes 36 saints with this title. Some of the most well-known include St. Augustine, St. Ambrose, St. Jerome, and St. Thomas Aquinas.
The formal designation of “doctor of the church” began in the Middle Ages, when the church wanted to recognize certain saints who had made exceptional contributions to theological learning. The process of being named a doctor involved a detailed review by Rome of the individual’s written work to ensure orthodoxy and significance of contributions. Female saints such as St. Catherine of Siena and St. Teresa of Avila have been named doctors despite institutional obstacles that made it difficult for women to pursue academic theological writing historically.
While most doctors lived in the early and medieval church periods, some as recent as the 19th century have been given the title. To be named a doctor is one of the highest honors the Church can bestow on a saint, meaning their writings and ideas are considered both influential and completely aligned with official church teaching. Some of the common criteria for being designated include:
- Making a significant contribution to theological understanding on critical church topics
- Producing a large body of written work, usually including commentaries on Scripture
- Being cited, studied, and built upon by later scholars and theologians
- Showing holiness and wisdom in applying theology to pastoral leadership
- Defending church teaching against heresy and false doctrine
While not exhaustive, the following are short biographies of some of the most prominent doctors of the church and their contributions:
St. Augustine of Hippo (354 – 430 AD)
St. Augustine is one of the best-known doctors and had an enormous impact on Western Christianity’s development, particularly influencing Protestant reformers like Martin Luther. After converting to Christianity from a worldly life, Augustine served as Bishop of Hippo Regius in Roman Africa. His most famous works include his Confessions and City of God. He wrote extensively on topics like original sin, just war theory, and the Trinity. Augustine shaped the church’s doctrine of grace and divine providence by arguing salvation was entirely an act of God, not human work.
St. Ambrose (340 – 397 AD)
St. Ambrose was known as the “Honey-Tongued Doctor” for his eloquent preaching and writing. He also had a significant role in converting Augustine to Christianity. As the Bishop of Milan, Ambrose defended orthodoxy against the heresy of Arianism, which denied the divinity of Christ. His treatise On the Duties of the Clergy set down important ethical and moral guidelines for priests and bishops. Ambrose also helped promote asceticism in the Western church as well as the cult of the saints and relics. Politically, he asserted the independence of the church from imperial power.
St. Jerome (342 – 420 AD)
St. Jerome was a monk and intellectual who produced one of early Christianity’s most enduring contributions – the Vulgate, a Latin translation of the Bible that became the standard version for over a thousand years. Jerome was also a historian and translated many theological texts into Latin from Greek. Known for his short temper, Jerome engaged in numerous theological disputes, but ultimately defended orthodoxy against Pelagianism which claimed humans could earn salvation through good works alone. Jerome’s letters and commentaries on Scripture are still widely read today.
St. Gregory the Great (540 – 604 AD)
Pope Gregory I, or Gregory the Great, reformed the papacy and helped strengthen the church’s independence from the state. He revised church liturgy and promoted monasticism and mission work. Gregory wrote extensively on practical spirituality in works like The Book of Pastoral Rule. He emphasized a contemplative approach to Scripture and the allegorical meaning behind texts. Gregory sent missionaries to evangelize England and promoted the concept of purgatory. He is also known for Gregorian chant, a form of medieval sacred music.
St. Thomas Aquinas (1225 – 1274 AD)
A medieval Dominican friar and one of the most influential theologians in church history, Aquinas worked to revive the systematic theology of ancient Christian thinkers like Augustine. His major work, the Summa Theologica, is still widely studied today as a comprehensive overview of church teaching on faith and ethics. Aquinas argued for the complementarity of faith and reason, the idea they could work fruitfully together to discern truth. He drew extensively from the philosophy of Aristotle and worked to synthesize it with Christian revelation.
St. Catherine of Siena (1347 – 1380 AD)
St. Catherine was a Dominican laywoman known for her mystical visions and writings on spiritual growth. She played an active role in church politics and tried to end the Avignon papacy, in which popes resided in France instead of Rome. Catherine left over 400 letters as well as her Dialogue, which described conversations with God about achieving salvation. She argued for reforms to her fellow Dominicans and criticized church corruption, while affirming loyalty to the papacy itself. She was also devoted to serving the poor and sick.
St. Teresa of Avila (1515 – 1582 AD)
St. Teresa was a Spanish Carmelite nun and mystic who pursued contemplative prayer and emphasized personal communion with Christ. Her best-known books include The Way of Perfection and The Interior Castle, which described the soul’s journey towards God. Teresa worked to reform the Carmelite order by returning it to strict enclosure and austerity. Along with St. John of the Cross, she founded the Discalced (shoeless) Carmelites which focused on poverty and contemplation. Her writings are seen as some of the church’s greatest spiritual literature.
St. Therese of Lisieux (1873 – 1897 AD)
Joining a French Carmelite convent at age 15, Therese lived a hidden life but was posthumously revered for her simple yet profound spirituality focused on doing small acts of love. She offered up her prayers and sufferings for missionaries. Her memoir The Story of a Soul shared her “Little Way” of childlike trust and devotion to God’s will. Therese promised to spend her heaven praying for those still on earth. She was named a doctor of the church and patron saint of missionaries despite her young age and limited writing.
This overview covers some of the main doctors, but there are over 30 other saints who have been officially named doctors of the church for their service to theological understanding and spiritual wisdom. They include figures like Athanasius, John Chrysostom, Francis de Sales, Albert the Great, Bede the Venerable, Peter Damian, Bernard of Clairvaux, Alphonsus Liguori, John of Avila, and more. While coming from diverse times and places, the doctors exemplify saintly lives devoted to knowing and loving God through prayer, study, preaching, and defending the faith.