A moralist is someone who has very strong opinions about what is right and what is wrong. Most moralists are offended when other people don't share their values.
Morals — personal beliefs about what is good or acceptable behavior — are extremely important to a moralist. In fact, moralists tend to feel so strongly about their own rules that they expect others to follow them precisely. The earliest meaning of moralist was simply "moral person," although it came to mean "person who moralizes," or makes authoritative comments on moral issues, often with a sense of superiority. The Latin root word, moralis, means "pertaining to morals."