Other forms: apostatized; apostatizing; apostatizes
To apostatize is to give up a belief. Your best friend may do her best to sway you to change your basketball allegiance from the Celtics to the Lakers, but you refuse to apostatize.
When someone renounces their religious principles, leaving one faith for another or ceasing to believe at all, they apostatize. The Latin root, apostata, means "one who forsakes religion or faith." This is the most common way to use this verb, but it also works well for changes in political belief: "I never thought he'd apostatize, but he's now a registered Democrat."