Doctor of the Church in the context of "East-West Schism"

Thomas Aquinas OP (/əˈkwaɪnəs/ ə-KWY-nəs; Italian: Tommaso d'Aquino, lit. 'Thomas of Aquino'; c. 1225 – 7 March 1274) was an Italian Dominican friar and priest, the foremost Scholastic thinker, as well as one of the most influential philosophers and theologians in the Western tradition. A Doctor of the Church, he was from the county of Aquino in the Kingdom of Sicily.

Thomas was a proponent of natural theology and the father of a school of thought (encompassing both theology and philosophy) known as Thomism. He argued that God is the source of the light of natural reason and the light of faith. He embraced several ideas put forward by Aristotle and attempted to synthesize Aristotelian philosophy with the principles of Christianity. He has been described as "the most influential thinker of the medieval period" and "the greatest of the medieval philosopher-theologians". Thomas Aquinas's philosophy influenced modern virtue ethics, aesthetics, and cognitive theory. He has been criticized, notably by Bertrand Russell, for seeking to justify conclusions already dictated by faith rather than follow reason independently.

Cyril of Alexandria (Ancient Greek: Κύριλλος Ἀλεξανδρείας; Coptic: Ⲡⲁⲡⲁ Ⲕⲩⲣⲓⲗⲗⲟⲩ ⲁ̅ or Coptic: Ⲡⲓⲁⲅⲓⲟⲥ Ⲁⲃⲃⲁ Ⲕⲩⲣⲓⲗⲗⲟⲥ ⲡⲓⲥⲧⲩⲗⲗⲟⲥ ⲛ̀ⲧⲉ ⲡⲓⲛⲁϩϯ or ⲡⲓ̀ⲁⲅⲓⲟⲥ Ⲕⲓⲣⲓⲗⲗⲟⲥ; c. 376–444) was the Patriarch of Alexandria from 412 to 444. He was enthroned when the city was at the height of its influence and power within the Roman Empire. Cyril wrote extensively and was a major player in the Christological controversies of the late 4th and 5th centuries. He was a central figure in the Council of Ephesus in 431, which led to the deposition of Nestorius as Patriarch of Constantinople.

Cyril is counted among the Church Fathers and also as a Doctor of the Church, and his reputation within the Christian world has resulted in his titles Pillar of Faith and Seal of all the Fathers. The Nestorian bishops at their synod at the Council of Ephesus declared him a heretic, labelling him as a "monster, born and educated for the destruction of the church".

John Chrysostom (/ˈkrɪsəstəm, krɪˈsɒstəm/; Greek: Ἰωάννης ὁ Χρυσόστομος, Latin: Ioannes Chrysostomus; c. 347 – 14 September 407) was an important Church Father who served as Archbishop of Constantinople. He is known for his preaching and public speaking, his denunciation of abuse of authority by both ecclesiastical and political leaders, his Divine Liturgy of Saint John Chrysostom, and his ascetic sensibilities. He was also the author of Adversus Judaeos and was strongly against Judaism. The epithet Χρυσόστομος (Chrysostomos, anglicized as Chrysostom) means "golden-mouthed" in Greek and denotes his celebrated eloquence. Chrysostom was among the most prolific authors in the early Christian Church.

He is honored as a saint in the Eastern Orthodox, Oriental Orthodox, Catholic, Anglican, and Lutheran churches, as well as in some others. The Eastern Orthodox, together with the Byzantine Catholics, hold him in special regard as one of the Three Holy Hierarchs (alongside Basil of Caesarea and Gregory of Nazianzus). Along with them and Athanasius of Alexandria he is also regarded as one of the four Great Greek Church Fathers. The feast days of John Chrysostom in the Eastern Orthodox Church are 14 September, 13 November and 27 January. In the Catholic Church, he is recognised as a Doctor of the Church. Because the date of his death is occupied by the feast of the Exaltation of the Holy Cross (14 September), the General Roman Calendar celebrates him since 1970 on the previous day, 13 September; from the 13th century to 1969 it did so on 27 January, the anniversary of the translation of his body to Constantinople. Of other Western churches, including Anglican provinces and Lutheran churches, some commemorate him on 13 September, others on 27 January. John Chrysostom is honored on the calendars of the Church of England and the Episcopal Church on 13 September. The Coptic Church also recognizes him as a saint (with feast days on 16 Thout and 17 Hathor).

Albertus Magnus OP (c. 1200 – 15 November 1280), also known as Saint Albert the Great, Albert of Swabia, Albert von Bollstadt, or Albert of Cologne, was a German Dominican friar, philosopher, scientist, and bishop. He is considered one of the greatest medieval philosophers and thinkers.

Canonized in 1931, he was known during his lifetime as Doctor universalis and Doctor expertus; late in his life the sobriquet Magnus was appended to his name. Scholars such as James A. Weisheipl and Joachim R. Söder have referred to him as the greatest German philosopher and theologian of the Middle Ages. The Catholic Church distinguishes him as one of the Doctors of the Church.

Pope Pius V, OP (Italian: Pio V; 17 January 1504 – 1 May 1572), born Antonio Ghislieri (and from 1518 called Michele Ghislieri), was head of the Catholic Church and ruler of the Papal States from 7 January 1566 to his death, in May 1572. He was an inquisitor and is venerated as a saint of the Catholic Church. He is chiefly notable for his role in the implementation of the Council of Trent, the Counter-Reformation, and the standardization of the Roman Rite within the Latin Church, known as the Tridentine mass. Pius V declared Thomas Aquinas a Doctor of the Church.

As a cardinal, Ghislieri gained a reputation for putting orthodoxy before personalities, prosecuting eight French bishops for heresy. He also stood firm against nepotism, rebuking his predecessor Pope Pius IV to his face when he wanted to make a 13-year-old member of his family a cardinal and subsidize a nephew from the papal treasury.

Caterina di Jacopo di Benincasa (25 March 1347 – 29 April 1380), known as Catherine of Siena, was an Italian mystic and pious laywoman who engaged in papal and Italian politics through extensive letter-writing and advocacy. Canonized in 1461, she is revered as a saint and as a Doctor of the Church due to her extensive theological authorship. She is also considered to have influenced Italian literature.

Born and raised in Siena, Catherine wanted from an early age to devote herself to God, against the will of her parents. She joined the "mantellates", a group of pious women, primarily widows, informally devoted to Dominican spirituality; later these types of urban pious groups would be formalized as the Third Order of the Dominicans, but not until after Catherine's death. Her influence with Pope Gregory XI played a role in his 1376 decision to leave Avignon for Rome. The Pope then sent Catherine to negotiate peace with the Florentine Republic. After Gregory XI's death (March 1378) and the conclusion of peace (July 1378), she returned to Siena. She dictated to secretaries her set of spiritual treatises, The Dialogue of Divine Providence. The Great Schism of the West led Catherine of Siena to go to Rome with the pope. She sent numerous letters to princes and cardinals to promote obedience to Pope Urban VI and to defend what she calls the "vessel of the Church". She died on 29 April 1380, exhausted by her rigorous fasting. Urban VI celebrated her funeral and burial in the Basilica of Santa Maria sopra Minerva in Rome.

Cyril of Jerusalem (Greek: Κύριλλος Α΄ Ἱεροσολύμων, Kýrillos A΄ Hierosolýmōn; Latin: Cyrillus Hierosolymitanus; c. 313 – 386) was a theologian of the Early Church. About the end of AD 350, he succeeded Maximus as Bishop of Jerusalem, but was exiled on more than one occasion due to the enmity of Acacius of Caesarea, and the policies of various emperors. Cyril left important writings documenting the instruction of catechumens and the order of the Liturgy in his day.

Cyril is venerated as a saint within the Roman Catholic Church, the Eastern Orthodox Church, Oriental Orthodox Church, and the Anglican Communion. In 1883, Cyril was declared a Doctor of the Church by Pope Leo XIII.

The Summa Theologiae or Summa Theologica (transl. 'Summary of Theology'), often referred to simply as the Summa, is the best-known work of Thomas Aquinas (1225–1274), a scholastic theologian and Doctor of the Church. It is a compendium of all of the main theological teachings of the Catholic Church, intended to be an instructional guide for theology students, including seminarians and the literate laity. Presenting the reasoning for almost all points of Christian theology in the West, topics of the Summa follow the following cycle: God; Creation, Man; Man's purpose; Christ; the Sacraments; and back to God.

Although unfinished, it is "one of the classics of the history of philosophy and one of the most influential works of Western literature". It remains Aquinas's "most perfect work, the fruit of his mature years, in which the thought of his whole life is condensed".

The cardinal virtues are four virtues of mind and character in classical philosophy. They are prudence, justice, fortitude, and temperance. They form a virtue theory of ethics. The term cardinal comes from the Latin cardo (hinge); these four virtues are called "cardinal" because all other virtues fall under them and hinge upon them.

These virtues derive initially from Plato in Republic Book IV, 426-435. Aristotle expounded them systematically in the Nicomachean Ethics. They were also recognized by the Stoics and Cicero expanded on them. In the Christian tradition, they are also listed in the Deuterocanonical books in Wisdom of Solomon 8:7 and 4 Maccabees 1:18–19, and the Doctors Ambrose, Augustine, and Aquinas expounded their supernatural counterparts, the three theological virtues of faith, hope, and charity.