Following the Apostles during the Biblical period, and after the Apostolic Fathers, Christianity continued to grow and develop both in numbers of converts and intellectual figures, even in the midst of persecution under the Roman Empire. Written works from several of Christian Figures in the late Second Century engaged with both heretical ideas and the Roman culture at large.

Justin Martyr (100 – 165 CE)

Justin Martyr was a Greek apologist and philosopher who was instrumental in the early intellectual defenses of Christianity in the century after the Apostles. He was one of the more profligate Christian figures of the second century, and was even acknowledged by the Apostolic Father Irenaeus. Justin wrote the Dialogue with Trypho, in which he details his own conversion to Christianity after rejecting several Greek philosophical movements.

Justin’s First Apology is his most well-known work. It is a defense of Christianity written to Roman Emperor Antoninus Pius, who was actively persecuting Christians for not giving worship to the emperor and Roman gods. The word apology is a Latin term which means a defense of one’s opinion – from it we get the English word apologetics, which often refers to the study of the defense of one’s religious claims. In his Apology, Justin argues against the persecution against Christians solely for their religious beliefs. He also argues that Christianity contains the full truth, and other religions only have partial access to the truth. Justin’s other works cover much in the way of early Christian theology, particularly Christology and the prophecies made by the Apostle John in the book of Revelation.

Justin was eventually beheaded for not making sacrifices to the Roman gods. His possible final words were, “That is our desire, to be tortured for Our Lord, Jesus Christ, and so to be saved, for that will give us salvation and firm confidence at the more terrible universal tribunal of Our Lord and Savior. And all the martyrs said: Do as you wish; for we are Christians, and we do not sacrifice to idols.”

Tertullian (155 – 220 CE)

Tertullian was a Carthaginian teacher and writer, fluent in both Greek and Latin. Many of his works were written in opposition to heresies within the church, such as Gnosticism or Marcionism. He also wrote some works in defense of Christianity to Roman government officials, and quoted from many books of the New Testament in his works. Later, he was drawn to Montanism, a belief system considered heretical by Christianity due to its views on prophecy and some other matters.

Tertullian, despite his writings in support of Christianity, is not hailed by Catholicism as a church father due to his non-orthodox views of the Trinity and his support for Montanism. It is speculated that, instead of being martyred like many of his contemporaries, he died of old age.

Iranaeus of Lyons (130-202 CE)

Iranaeus of Lyons was a student of the Apostolic father Polycarp, a student directly taught by the Apostle John. His Against Heresies is one of the first post-Biblical apologetic works, and contains some of the first references to the four Gospels (the New Testament books Matthew, Mark, Luke, and John) and some of the writings of Paul. Against Heresies is an argument against various religious ideas that arose both during and shortly after the time of the Apostles, such as Gnosticism and Marcionism.

Little is known about the life of Iraneus outside of his writings. He was probably raised in Smyrna (in modern-day Turkey), and moved to Lyons, France around 177. He was traveling to Rome with a message for the Roman church when a persecution and martyrdom of 46 Christian figures was carried out in Lyons under false charges. The Bishop of Lyons, Pothinus, was among those killed. Irenaeus would assume the position of Bishop of Lyons upon his return. While the specific circumstances of his death are unknown, Iranaeus is considered a martyr.

Clement of Alexandria (150-215 CE)

Clement of Alexandria was a highly regarded theologian and philosopher, both in early Christianity and among modern scholarship. Though raised as a pagan, Clement later converted to Christianity after finding pagan religions to have more questionable morality than what Christianity offered. He eventually made his way to Alexandria in Egypt, where an early school called the Catechetical School of Alexandria met. Clement would become the “dean” of the school and influence other early Christian figures, theologians and thinkers, such as Origen and Jerome.

Clement’s major contributions were a trilogy of works – the Protrepticus, the Paedagogus, and the Stromata. The Protrepticus (Exhortation) is an evangelical work that encourages Greek pagans to adopt Christianity, and contrasts pagan Greek religious practices with Christianity. The Paedagogus (tutor) focuses on Jesus Christ and His moral example, encouraging Christians to live moral lives. Finally, the Stromata (Miscellanies) is a collection of various other topics as the name implies. It covers Greek philosophy, faith, asceticism, and other topics.

Christianity in the second century dealt with multiple interpretations of many of the same things written by the Apostles, such as Gnosticism and its various developments. It also had to deal with consistent persecution from Roman officials, as many misconceptions of Christianity abounded by the Romans.