Is it just me or do most people seem to misread this statement? It reads: Congress shall make no law respecting an establishment of religion. Most people I talk to seem to think this simply means that congress can't establish an official religion. But for me, the obvious interpretation is something more. Christianity is an establishment of religion. Judaism is an establishment of religion. The Church of the Flying Spaghetti Monster is an establishment of religion. The First Amendment says that congress can't make a law that respects one of these, meaning it can't deliberately favor one over another, or one over none.

A law made for religious reasons is a violation of this. Congress passing a law that, for example, bans homosexual behavior or denies rights based on homosexuality, encourages prayer or other religious rituals, or bans long hair on men or short hair on women (something which the Bible shames), for reasons based on religious teachings, would clearly be respecting one or more establishments of religion and would thus be unconstitutional. If the reasons have solid roots in science that few can contest, that's a different story. For example, most religions outlaw murder, but we legally outlaw it because it presents a clear and demonstrable threat to society, not just because the religions say so.