The Aegean is also the water on which the earliest Christian expansion outside the Levant took place, and the Acts of the Apostles reads in places like a shipping itinerary.
Paul crosses from Asia Minor into Macedonia and works down through Philippi, Thessalonica and Beroea to Athens and Corinth; later journeys take him to Ephesus for an extended stay, back across to Troas, and eventually toward Rome. The congregations founded on those coasts are the recipients of most of the surviving letters, and the arguments in them, about food offered to idols, about the resurrection, about whether gentile converts must keep the law, are arguments taking place in port cities where several religions were already competing for the same audiences.
Ephesus is the clearest case. It held the temple of Artemis, one of the largest religious structures in the Greek world and a major economic institution, and Acts records a riot provoked by silversmiths who made shrines of the goddess and saw their trade threatened. Whatever the details, the account describes a real economy of devotion that a new movement disrupted.
Patmos, a small island off the Ionian coast, is where the book of Revelation places its author, in exile. Its monastery of Saint John, founded in 1088, and the cave identified as the site of the vision have drawn pilgrims for a thousand years, and the island remains an Orthodox destination.
Sources The New Testament, Acts of the ApostlesAnonymous with The New Testament, RevelationTraditionally attributed to John of Patmos