apostasy
n.the act of leaving a religion or a political group that you were a member of. It is often seen as a very serious or shocking choice.
n.the formal renunciation of a religion, political party, or other group to which one previously belonged. Often carries a strong negative or scandalous connotation.
“The leader's apostasy caused a major split in the party.”
“The former minister's public apostasy from the party's core values led to his immediate resignation.”
“Historians often debate whether the emperor's apostasy was a calculated political move or a genuine crisis of faith that destabilized the empire.”
From Latin apostasia, from Ancient Greek ἀποστασία (apostasía, “defection, revolt”), from ἀφίστημι (aphístēmi, “I withdraw, revolt”), from ἀπό (apó, “from”) + ἵστημι (hístēmi, “I stand”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.