The Apostolic Fathers were core Christian theologians among the Church Fathers who lived in the 1st and 2nd centuries AD, who are believed to have personally known some of the Twelve Apostles or to have been significantly influenced by them. Their writings, though widely circulated in Early Christianity, were not included in the canon of the New Testament. Many of the writings derive from the same time period and geographical location as other works of early Christian literature that came to be part of the New Testament. Some of the writings found among the Apostolic Fathers appear to have been as highly regarded as some of the writings which became the New Testament.
Saint Polycarp (†155) was a disciple of Saint John the Apostle ordained by him bishop of Smyrna who died a martyr, bound and burned at the stake, then stabbed when the fire failed to touch him. With Clement of Rome and Ignatius of Antioch, Polycarp is regarded as one of three chief Apostolic Fathers and is regarded as a saint and Church Father in the Eastern Orthodox, Oriental Orthodox, Catholic, Anglican, and Lutheran churches. His feast day is commemorated on February 23.
Ignatius of Antioch (†c. 107), also known as Ignatius Theophorus was an early Christian writer and bishop of Antioch. En route to Rome, where he met his martyrdom, Ignatius wrote a series of letters which now form a central part of the later collection known as the Apostolic Fathers and serve as an example of early Christian theology. Important topics they address include ecclesiology, the sacraments, and the role of bishops. In speaking of the authority of the church, he was the first to use the phrase "catholic church" in writing, which is still in use to this day. His feast day was kept in his own Antioch on 17 October, the day on which he is now celebrated in the Catholic Church and generally in western Christianity. In the Eastern Orthodox Church, it is observed on 20 December.