The volume collects selected papers from the fifth annual APECSS conference which focused on the topic of letters from Christian Antiquity. The conference papers deal with epistolography from the apostle Paul up to Theodore the Studite (ninth century), considered in different aspects, namely, historiography of studies, literary form, Church history, dogmatic contents, attribution, etc. Other patristic studies include hagiography, liturgics, Christian art, early Egyptian monasticism, Islamic-Christian relations in the Middle Ages, and the Jewish background of Christianity.