Apostasy (
Greek απο,
apo, "away, apart", στασις,
stasis, "standing") is the renunciation of one's
religion. It is customarily considered a
vice, a corruption of the
virtue of
piety in the sense that when piety fails, apostasy is the result. However, most
converts[?] to a new religion can also be considered apostates from a previous belief. The word is also used to refer to renunciation of belief in a cause other than religion.
One who is "guilty" of apostasy is a apostate, or one who apostatizes.
See Virtue and Great Apostasy.