Minucius Felix
Marcus Minucius Felix was a Roman advocate, probably active in the late second or early third century AD (the dating is fiercely disputed). His sole surviving work, the Octavius, is a dialogue between a Christian named Octavius Januarius and a pagan named Caecilius Natalis, with Minucius himself as narrator and arbiter. It is set on the beach at Ostia, and its literary model is clearly Cicero's dialogues.
The Octavius is remarkable for what it does not contain: there is almost no specifically Christian theology. No mention of Christ, the incarnation, the resurrection, or scripture. The argument is conducted entirely on philosophical grounds — monotheism is demonstrated from Stoic and Platonic premises, pagan mythology is dismantled by reason, and the moral superiority of the Christian life is presented without appeal to revelation. Whether this represents sophisticated apologetic strategy (meeting pagans on their own ground) or Minucius's own philosophical Christianity is debated.
It is the earliest surviving work of Latin Christian prose (if it predates Tertullian, which is uncertain), and one of the most elegant.