Sozopol was Christianized early. Bishops are recorded as resident there from at least 431. At least eight bishops are known (Le Quien, Oriens christianus, I, 1181): Athanasius (431), Peter (680), Euthymius (787) and Ignatius (869); Theodosius (1357), Joannicius, who became Patriarch of Constantinople (1524), Philotheus (1564) and Joasaph (1721).