From the Greek apo, "away from," and stasis "standing," literally meaning a "standing apart," apostasy is used in Christian theology to speak of total renunciation of faith in Christ and abandonment of Christianity. It has always been considered to be among the most serious sins. Apostasy was regarded as unforgivable in the post-apostolic church. However, the magnitude of defections during the Decian persecutions in 250 compelled the church to apply its gospel of forgiveness to apostates. Hippolytus and Tertullian were rigorists in the discussion, but Callistus advocated a more merciful course. Cyprian required rebaptism.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.