Polycarp of Smyrna
Polycarp lived through the second half of the first century AD and the first half of the second century. From a statement he is recorded to have made at his martyrdom, it is assumed that Polycarp was baptized as a child and didn’t have a moment in his life where he did not know the Lord. He had great influence in the early Christian Church, largely because he was a disciple of the Apostle John. His apostolic connection helped land him the Bishop office of Smyrna, and it also placed him in a very important role of preserving the orthodox teachings of the Apostles, which he did with tenacity. It is reported that he called Marcion out to his face in Rome, calling him “the first born of Satan.” He also pulled believers away from Gnosticism. His willingness to die as a 2nd generation Church Father was another way in which he carried on like the apostles (all except John that is). Today his writings only have survived through a letter he wrote to the Philippians, which is an important text for the modern church since it is one of the earliest writings we have from Christendom outside of the Biblical texts.
Irenaeus of Lyons
Irenaeus was born in Smyrna in the first half of the second century AD and he lived to see the close of that century. Having been a student of Polycarp in his youth, becoming the Bishop of Lyons late in his life, he carried on a chain of successive leadership tracing back to the apostles. In fact, Irenaeus prescribed such connection to apostolic succession for all bishops, stressing that they all taught what the apostles had received from Christ and passed on to followers such as his teacher, Polycarp. It is on this authority that he spoke against the Gnostics who claimed to have a knowledge from outside of direct revelation from Jesus. His refutation of the Gnostics, in particular the flavor of Gnosticism that derived from the followers of Valentinus, has been preserved in his work Against Heresies. It is from this work that the modern Church had the most information about Gnosticism before the discovery of the Dead Sea Scrolls. His writings also prove helpful to demonstrate the early formation of the New Testament Canon, since Irenaeus’s writings provide the first record of acknowledging a four-fold Gospel in Church writing and he references every text of the New Testament, except 3 John, in Against Heresies. He may, or may not have died as a martyr.
Jerome
Jerome, AKA Eusebius Hieronymus, was born in Stridon just prior to the middle of the fourth century AD, dying around 420 AD. In is lifetime he practiced monasticism as a desert hermit, was ordained a priest, served as a secretary to Pope Damascus, and helped found a monastery in Bethlehem. Jerome was a prolific translator, translating numerous sermons and commentaries of Church Father Origen, for instance. His greatest and most long-lasting impact on the Church was his translation of the Vulgate (Latin) Bible. His translation work, in particular on revisions of the Septuagint (Greek version of the New Testament) led him to the understanding that the only inspired text of the Bible is that of the original text. In addition to his translations, he added much to the Church’s collection of exegetical commentaries as well as throwing his hat into to the arguments of doctrinal discussion in his day concerning the value of virginity compared to marriage, the ever-virgin state of Mary, the value of asceticism, defending the use of the work of Origen, and writing against Pelagianism (though Jerome was likely a synergist himself).
The Cappadocian Fathers
Arius was an early fourth century priest who taught that Jesus was not eternal. He taught that Jesus was a created being. To formulate a catholic response to the teachings of Arius was the main reason Emperor Constantine I called the Council of Nicaea in 325 AD. This council rejected Arius’ teachings (Arianism) and formulated the Nicene Creed as a proper Trinitarian statement, which adopted the term “of one substance” to refer to describe the oneness in divinity that the Father, Son, and Holy Spirit all shared. After the council, not every church bishop kept to Nicene Creed and fell back to Arianism. Soon after the Nicene Creed, Gregory of Nazianzus, Basil of Caesarea, and Basil’s brother, Gregory of Nyssa, were born. All three were from Cappadocia and they were friends and worked together to advance and cement the formed language of the Trinity that God exists as three persons in one essence. Their preaching and writing was significant in putting an end to Arianism in the fourth century and was crucial in the Council of Constantinople in 381 that re-affirmed the Nicene Creed. Together these three men are known as the Cappadocian Fathers.
John Chrysostom
John Chrysostom (347–407 AD) was born John in Syrian Antioch. He was appointed as the Bishop of Constantinople in 398. Chrysostomos means “golden-mouth” and is added to his given name as a result of his powerful sermons. His homilies focused on living the crucified life and railed against the excesses and sinful indulgences of his day that were woefully present in the upper-echelon of the secular world and even the Church. Many loved his proclamations, but those on high did not appreciate his pointed applications at them, so he was deposed from this position and then sent into exile where he died. Around 600 of his homilies survive today.
Andy Wrasman 
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