Eusebius of Caesarea, also called Eusebius Pamphili (flourished 4th century, Caesarea Palestinae, Palestine), bishop, exegete, polemicist, and historian whose account of the first centuries of Christianity, in his Ecclesiastical History, is a landmark in Christian historiography. He is also considered as one of the "Father of Church History." He was born about 260 and died before 341.
St. Athanasius, also called Saint Athanasius of Alexandria or Saint Athanasius the Apostolic (born c. 293, Alexandria—died May 2, 373, Alexandria; feast day May 2), theologian, ecclesiastical statesman, and Egyptian national leader. He was the chief defender of Christian orthodoxy in the 4th-century battle against Arianism, the heresy that the Son of God was a creature of like, but not of the same, substance as God the Father. His important works include The Life of St. Antony, On the Incarnation, and Four Orations Against the Arians
Saint Hilary of Poitiers (c. 300 – 368 C.E.), also known as Hilarius, was bishop of Poitiers in Gaul (today's France) and an eminent doctor of the Western Christian Church. A sometimes persecuted champion against the theological movement of Arianism, he was known as the "Athanasius of the West."
Saint Cyril of Jerusalem, (born c. 315, Jerusalem—died 386?, Jerusalem; feast day March 18), bishop of Jerusalem and doctor of the church who fostered the development of the “holy city” as a pilgrimage centre for all Christendom.
A senior presbyter when he succeeded Maximus as bishop (c. 350), Cyril was exiled about 357 and at two later times from his see by the Arians. Many years later at the Council of Constantinople (381) there was evidence that he might have been suspected by the strictly orthodox for his associations with the Homoiousians (moderate Arians), who had reinstated him as bishop at the Council of Seleucia (359). He retained his bishopric during the reign of Emperor Julian the Apostate (361–363).
Cyril’s primary surviving work is a collection of 23 catechetical lectures (Catecheses) delivered to candidates for Baptism. The first 18, based on the Jerusalem baptismal creed, were given during Lent, and the concluding 5 instructed the newly baptized during the week after Easter. Cyril was declared a doctor of the church in 1883.
Saint Gregory of Nazianzus (329–January 25, 389 C.E.), also known as Saint Gregory the Theologian or Gregory Nazianzen, was a fourth century C.E. Christian poet, orator, and theologian, who, quite against his will and temperament, was appointed bishop of Constantinople. In this role, Gregory made a significant impact on the shape of Trinitarian theology in both the Greek-speaking and Latin-speaking worlds, and he is remembered as the "Trinitarian Theologian." Given the prevalence of Arianism throughout Eastern Christendom at the time of his appointment, he (along with Athanasius of Alexandria) was instrumental in defining and defending the understanding of God forwarded by the Council of Nicea. Futher, much of his theological work was so central to the development of Christian dogma that it continues to influence modern theologians, especially in regard to the relationship between the three persons of the Trinity.
The promulgation of his (at times contested) theological perspectives was aided by the fact that Gregory was widely considered one of the most accomplished rhetorical stylists of the patristic age. As a classically trained speaker and philosopher he infused Hellenic styles and approaches (in terms of poetry and oratory) into the early church, establishing a paradigm that Byzantine theologians and church officials would continue to follow to the present day.
Basil of Caesarea (ca. 330 - January 1, 379 C.E.) (Latin: Basilius), also called Saint Basil the Great (Greek: Άγιος Βασίλειος ο Μέγας), was the Bishop of Caesarea and a leading churchman in the fourth century. The Eastern Orthodox Church and Eastern Catholic Churches consider him a saint and one of the Three Holy Hierarchs (together with Gregory Nazianzus and John Chrysostom). Likewise, the Roman Catholic Church considers him a saint and a Doctor of the Church. The principal theological writings of Basil are his De Spiritu Sancto, a lucid and edifying appeal to Scripture and early Christian tradition (to prove the divinity of the Holy Spirit), and his Refutation of the Apology of the Impious Eunomius, written in 363 or 364, three books against Eunomius of Cyzicus, the chief exponent of Anomoian Arianism.
Gregory of Nyssa (Latin:Gregorius Nyssenus, Greek: Άγιος Γρηγόριος Νύσσης) (ca. 335–ca. 394 C.E.) was a Christian bishop and saint. He was a younger brother of Basil the Great, and a good friend of Gregory Nazianzus. These three saints, collectively referred to as the Cappadocian Fathers, were instrumental in defining and defending Christian theology during a particularly volatile period of theological development. Among this august company, Gregory "was, by most reckoning, the greatest speculative theologian of the three. Gregory is remembered above all for two major contributions to theology. The first is his doctrine of the Trinity, a development of the theology of Basil and their mutual friend Gregory Nazianzus. Following Basil's lead, Gregory argues that the three Persons of the Trinity can be understood along the model of three members of a single class: thus, the Father, Son, and Holy Spirit are three in the same way that Peter, Paul, and Timothy are three men. So why do we not say there are three Gods? Gregory answers that, normally, we can distinguish between different members of the same class by the fact that they have different shapes, sizes, and colors. Even if they are identical, they still occupy different points in space. But none of this is true of incorporeal beings like God. Even lesser spiritual beings can still be distinguished by their varying degrees of goodness, but this does not apply to God either. In fact, the only way to tell the three Persons apart is by their mutual relations—thus, the only difference between the Father and the Son is that the former is the Father of the latter, and the latter is the Son of the former.
Saint Ambrose, Latin Ambrosius (born ad 339, Augusta Treverorum, Belgica, Gaul—died 397, Milan; feast day December 7), bishop of Milan, biblical critic, and initiator of ideas that provided a model for medieval conceptions of church–state relations. His literary works have been acclaimed as masterpieces of Latin eloquence, and his musical accomplishments are remembered in his hymns. Ambrose is also remembered as the teacher who converted and baptized St. Augustine of Hippo, the great Christian theologian, and as a model bishop who viewed the church as rising above the ruins of the Roman Empire.
St. John Chrysostom, (born 347 ce, Antioch, Syria—died September 14, 407, Comana, Helenopontus; Western feast day September 13; Eastern feast day November 13), early Church Father, biblical interpreter, and archbishop of Constantinople. The zeal and clarity of his preaching, which appealed especially to the common people, earned him the Greek surname meaning “golden-mouthed.” His tenure as archbishop was stormy, and he died in exile. His relics were brought back to Constantinople about 438, and he was later declared a doctor (teacher) of the church.
St. Jerome, Latin in full Eusebius Hieronymus, pseudonym Sophronius (born c. 347, Stridon, Dalmatia—died 419/420, Bethlehem, Palestine; feast day September 30), biblical translator and monastic leader, traditionally regarded as the most learned of the Latin Fathers. He lived for a time as a hermit, became a priest, served as secretary to Pope Damasus I, and about 389 established a monastery at Bethlehem. His numerous biblical, ascetical, monastic, and theological works profoundly influenced the early Middle Ages. He is known particularly for his Latin translation of the Bible, the Vulgate, and is considered a doctor of the church.
Saint Augustine, also called Saint Augustine of Hippo, original Latin name Aurelius Augustinus (born Nov. 13, 354, Tagaste, Numidia [now Souk Ahras, Algeria]—died Aug. 28, 430, Hippo Regius [now Annaba, Algeria]), feast day August 28, bishop of Hippo from 396 to 430, one of the Latin Fathers of the Church, one of the Doctors of the Church, and perhaps the most significant Christian thinker after St. Paul. Augustine’s adaptation of classical thought to Christian teaching created a theological system of great power and lasting influence. His numerous written works, the most important of which are Confessions and City of God, shaped the practice of biblical exegesis and helped lay the foundation for much of medieval and modern Christian thought.
Augustine is remarkable for what he did and extraordinary for what he wrote. If none of his written works had survived, he would still have been a figure to be reckoned with, but his stature would have been more nearly that of some of his contemporaries. However, more than five million words of his writings survive, virtually all displaying the strength and sharpness of his mind (and some limitations of range and learning) and some possessing the rare power to attract and hold the attention of readers in both his day and ours. His distinctive theological style shaped Latin Christianity in a way surpassed only by scripture itself. His work continues to hold contemporary relevance, in part because of his membership in a religious group that was dominant in the West in his time and remains so today.
Intellectually, Augustine represents the most influential adaptation of the ancient Platonic tradition with Christian ideas that ever occurred in the Latin Christian world. Augustine received the Platonic past in a far more limited and diluted way than did many of his Greek-speaking contemporaries, but his writings were so widely read and imitated throughout Latin Christendom that his particular synthesis of Christian, Roman, and Platonic traditions defined the terms for much later tradition and debate. Both modern Roman Catholic and Protestant Christianity owe much to Augustine, though in some ways each community has at times been embarrassed to own up to that allegiance in the face of irreconcilable elements in his thought. For example, Augustine has been cited as both a champion of human freedom and an articulate defender of divine predestination, and his views on sexuality were humane in intent but have often been received as oppressive in effect.