The Evil Day (1992)

A family whose descendants always turn into a bloodthirsty monster on their 18th birthday due to a druid curse. Today Michael turns 18 and his grandma gives him another Bible. But Michael doesn't want to know anything about it because he has money debts. Nothing happens when the debt collectors beat him up, but when they kill his grandmother in his absence, he freaks out and turns into a bloodthirsty monster.