John Chrysostom (c. 347–407, Greek: Ἰωάννης ὁ Χρυσόστομος), Archbishop of Constantinople, was an important Early Church Father. He is known for his eloquence in preaching and public speaking, his denunciation of abuse of authority by both ecclesiastical and political leaders, the Divine Liturgy of St. John Chrysostom, and his ascetic sensibilities. After his death in 407 (or, according to some sources, during his life) he was given the Greek epithet chrysostomos, meaning "golden mouthed", in English and Anglicized to Chrysostom. The Orthodox and Eastern Catholic Churches honor him as a saint and count him among the Three Holy Hierarchs, together with Basil the Great and Gregory Nazianzus. He is recognized by the Eastern Orthodox Church and the Catholic Church as a saint and as a Doctor of the Church. Churches of the Western tradition, including the Roman Catholic Church, some Anglican provinces, and parts of the Lutheran Church, commemorate him on 13 September. Some Lutheran and many Anglican provinces commemorate him on the traditional Eastern feast day of 27 January. The Coptic Orthodox Church of Alexandria also recognizes John Chrysostom as a saint (with feast days on 16 Thout and 17 Hathor). John is known in Christianity chiefly as a preacher, theologian and liturgist. Among his homilies, eight directed against Judaizing Christians remain controversial for their impact on the development of Christian antisemitism.

Nicholas Cabasilas (Greek: Νικόλαος Καβάσιλας; born 1319/1323 in Thessalonica; died 1392) was a Byzantine mystic and theological writer. Cabasilas is a saint within the Orthodox Church. His feast day is June 20. The Roman Catholic Church uses extracts from his Life in Christ as readings in the Liturgy of the Hours (Tuesday, Wednesday, and Thursday of the Fifth Week of Easter in Year II of the two-year cycle for the Office of Readings). He was on intimate terms with the emperor John VI Cantacuzene, whom he accompanied in his retirement to a monastery. He was once thought to have succeeded his uncle Nilus Cabasilas as archbishop of Thessalonica; however contemporary records of that see do not show Nicholas as serving in the capacity of archbishop. It is more likely that he served as a priest at the Manganon monastery near Constantinople. In the Hesychast controversy he took the side of the monks of Mount Athos and Saint Gregory Palamas. His chief work is his Περὶ τῆς ἐν Χριστῷ ζωῆς, ("On the Life in Christ"). in which he lays down the principle that union with Christ is effected by the three great mysteries of baptism, chrismation, and the eucharist. He also wrote homilies on various subjects, and a speech against usurers, printed with other works in Migne, Patrologia Graeca, c. i. A large number of his works is still extant in manuscript. Cabasilas' major works are Life in Christ and Commentary on the Divine Liturgy. These works display a profound understanding of the sacramental and liturgical life of the Eastern Orthodox Church and are accessible to and instructive for any Christian today worshiping in either the East or West.