With the gentle exception of the Blessed Virgin Mary, even among saints, there is a pecking order. There's a super-select group of 36 saints who are have shown themselves, by virtue of their lives and writing accomplishments, to be blessed with extraordinary wisdom and sanctity. They are known as “Doctors of the Church.”

All are men except for four: Sts. Hildegard of Bingen, Catherine of Siena, Teresa of Ávila and Thérèse of Lisieux.

To be declared a Doctor of the Church, a saint must have his writings examined to see if it’s impacted positively upon and contributed to the Church. However, this declaration does not necessarily mean that the saint’s writings are completely free from error. It simply means that it hasn’t negatively impacted the Church. The following is a list of the Doctors of the Church:

  1. St. Albert
  2. St. Alphonsus Liguori
  3. St. Ambrose of Milan
  4. St. Anselm
  5. St. Anthony of Padua
  6. St. Athanasius
  7. St. Augustine of Hippo
  8. St. Basil the Great
  9. St. Bede the Venerable
  10. St. Bernard of Clairvaux
  11. St. Bonaventure
  12. St. Catherine of Siena
  13. St. Cyril of Alexandria
  14. St. Cyril of Jerusalem
  15. St. Ephraem the Syrian
  16. St. Francis de Sales
  17. St. Gregory of Narek
  18. St. Gregory Nazianzus
  19. St. Gregory the Great
  20. St. Hilary of Poitiers
  21. St. Hildegard of Bingen
  22. St. Isidore of Seville
  23. St. Jerome
  24. St. John Chrysostom
  25. St. John Damascene
  26. St. John of Ávila
  27. St. John of the Cross
  28. St. Lawrence of Brindisi
  29. St. Leo the Great
  30. St. Peter Canisius
  31. St. Peter Chrysologus
  32. St. Peter Damian
  33. St. Robert Bellarmine
  34. St. Teresa of Ávila
  35. St. Thérèse of Lisieux
  36. St. Thomas Aquinas

Doctors of the Church are generally prolific writers. According to Pope Boniface VII’s Sixth Book of Decretals, the first four Doctors were honored in the early Middle Ages by the Latin Church and were known simply as “The Four Doctors” — St. Gregory the Great, Ambrose, Augustine and Jerome. The early Eastern Church recognized an additional four Doctors: Sts. John Chrysostom, Basil, Gregory Nazianzen and Athanasius.

Officially, to become a Doctor of the Church, the three requirements are eminens doctrina (i.e. eminent learning,) insignis vitae sanctitas (i.e., a high degree of sanctity) and ecclesiae nesthesia (i.e., proclamation by the Church.) Though Pope Benedict XIV taught that the declaration can come from the pope or a general council, no general councils have availed themselves of this option thus far.

Historically, the decree is issued by the Congregation of Sacred Rites or its successors and, after a careful examination of the saint’s writings, is approved by the pope. Currently, the process of investing new Doctors of the Church is being examined jointly by the Congregation for the Causes of Saints and the Congregation for the Doctrine of the Faith.

No martyr has ever been included on the list. Pope Benedict XIV specifically pointed out that Sts. Cyprian, Ignatius and Irenaeus aren’t Doctors, though their writings have contributed greatly to the Universal Church.

However, in Jesuit Fr. Giandomenico Mucci’s 1997 article “The Title of Doctor of the Church” published in La Civiltà Cattolica is a cornucopia of information about Vatican scuttlebutt about prospective Doctors.

In the article, Fr. Mucci, building on ideas formulated by Franciscan scholar Cardinal Umberto Betti ― elevated by Pope Benedict XVI in 2007 ― who advocated for investing martyrs as Doctors also. Technically, explained Cardinal Betti, there are no theological or canonical impediments to investing martyrs. However, he is hesitant about investing popes.

“Because the title of doctor of the Church,” he explains, “is based specifically on the eminens doctrina, it cannot be concealed under any gift of sanctity possessed by the candidate for the title of doctor. So even a martyr in whom the Church recognizes the eminens doctrina (e.g., Ignatius, Irenaeus, Cyprian) can be elevated to the doctorate, despite the different historical practice.”

However, Mucci explains that, “It seems problematic, to grant the title of Doctor of the universal Church to a saint who was a Roman pontiff. In fact, the documents of his magisterium are authoritative not because of the eminens doctrina possessed as a personal gift of grace, but by virtue of the office that constituted him supreme pastor and doctor of all the faithful.”

According to the same article, there are fifteen additional “dotoribile” ― doctors-in-waiting ― who may someday become invested.

In his article, Fr. Mucci listed the saints and blesseds on the waiting list for the title of Doctor of the Church:

  1. St. Veronica Giuliani
  2. St. Gertrude of Helfta
  3. St. Bridget of Sweden
  4. St. Margaret Mary Alacoque
  5. Bl. Julian of Norwich
  6. St. John Bosco
  7. Sts. Cyril and Methodius
  8. St. Lorenzo Giustiniani
  9. St. Antonino of Florence
  10. St. Thomas of Villanova
  11. St. Ignatius of Loyola
  12. St. Vincent de Paul
  13. St. Louis-Marie Grignion de Montfort
  14. St. Bernardino of Siena

Apparently, St. Bernardino of Siena may be the next saint invested as Doctor. He seems to only lack a final okay from Pope Francis.