Teaching Terror as a Moral Obligation and the First Amendment

I think the question whether teaching that the practice of terror is a moral obligation is constitutionally protected primarily raises free speech issues (not freedom of religion issues), and under current law, the rules dictate that the facts are important. E.g., Yates, Brandenburg, Scales, Noto.   If the method of teaching is not constitutionally protected under the speech clause, it is not constitutionally protected under the free exercise clause, and government can subsidize protected speech while refusing to subsidize unprotected speech without establishment clause difficulties. Many argue that the free speech regime is too speech protective in this context, and whether they are right or wrong, it seems to me that they are focusing on the key issue. It does not matter whether the speakers are religious or not in this context.