1. the abandonment of a religious faith, belief, or practice
Usage: often used in religious or theological contexts
2. the abandonment of a political party, cause, or principle
Usage: extended use beyond religious contexts

Examples

• His apostasy from the church shocked his family.
• The politician was accused of apostasy for abandoning the party's core principles.
• In some religions, apostasy is considered a serious offense.
• She committed apostasy by publicly rejecting the beliefs she had held for decades.
• The historical record shows many instances of apostasy during times of persecution.
• His apostasy was motivated by a change in personal convictions.