Lucius Caecilius Firmianus Lactantius was an early Christian author (ca. 240 – ca. 320) who became an advisor to the first Christian Roman emperor, Constantine I, guiding his religious policy as it developed, and tutor to his son.

Lactantius, a Latin-speaking native of North Africa, was a pupil of Arnobius and taught rhetoric in various cities of the Eastern Roman Empire, ending in Constantinople. He wrote apologetic works explaining Christianity in terms that would be palatable to educated people who still practiced the traditional religions of the Empire, while defending Christian beliefs against the criticisms of Hellene philosophers. His Divinae Institutiones ("Divine Institutes") is an early example of a systematic presentation of Christian thought. He was considered somewhat heretical after his death, but Renaissance humanists took a renewed interest in him, more for his elaborately rhetorical Latin style than for his theology.

A translator of the Divine Institutes starts his introduction as follows:

Justin Martyr, also known as just Saint Justin (AD 100–165), was an early Christian apologist, and is regarded as the foremost interpreter of the theory of the Logos in the 2nd century. Most of his works are lost, but two apologies and a dialogue did survive. He is considered a saint by the Roman Catholic Church and the Eastern Orthodox Church.

Most of what is known about the life of Justin Martyr comes from his own writings. He was born at Flavia Neapolis (today Nablus) in Palestine into a pagan family, and defined himself as a Gentile. His grandfather, Bacchius, had a Greek name, while his father, Priscus bore a Latin name, which has led to speculations that his ancestors may have settled in Neapolis soon after its establishment or that they may have descended from a Roman 'diplomatic' community that had been sent there. He received a Greek education. He tells us (Dialogue 2-8) that he tried first the school of a Stoic philosopher, who was unable to explain God's being to him. He then attended a Peripatetic philosopher but was put off because the philosopher was too eager for his fee. Then he went to hear a Pythagorean philosopher, who demanded that he first learn music, astronomy and geometry, which he did not wish to do. Subsequently, he adopted Platonism after encountering a Platonist thinker who had recently settled in his city. Some time afterwards, he chanced upon an old man, possibly a Palestinian or Syrian Christian, in the vicinity of the seashore, who engaged him in a dialogue about God, and spoke of the testimony of the prophets as more reliable than the reasoning of philosophers. It was this argument which, Justin avers, kindled in him a love of Christ, and led him to embrace the Christian faith. He was influenced in this by the fearless conduct of the Christians facing execution (Apol. 2:12). His conversion is commonly assumed to have taken place at Ephesus, though it may have occurred anywhere on the road from Palestine to Rome.