It can be difficult for extremists on the Christian Right to convince everyone else that their desire to discriminate against gays, women, atheists, and sundry non-Christians is justified or appropriate in America. The "American Way" is supposed to be freedom and equality, not privilege and discrimination. This means that the best tactic for convincing others that discrimination and oppression are necessary is to convince them that it's somehow to preserve freedom. It's an Orwellian tactic to get people to believe that War is Peace in this manner, but it can be amazingly persuasive if framed correctly.
For Christian Nationalists, the basic argument they use runs something like this: denying Christians the ability to discriminate against gays prevents them from freely "exercising" their religious beliefs that homosexuality is immoral. Therefore, denying Christians the ability to discrimination is an unconstitutional infringement on their First Amendment rights. Godless Sodomites are thus the enemy of Christianity, of biblical scriptures, and of basic religious liberties. A similar argument can be made for all the other groups Christian Nationalists would discriminate against. If you believe this, then you have been convinced that discriminating against gays and infringing on their civil liberties is necessary to protect the religious liberties of Christian extremists.
A more extreme version of this argument, promulgated by even more extreme Christians, is the that gays, atheists, secularists, and others are involved in a conspiracy to destroy Christianity itself. Whether knowingly in league with Satan or merely unwitting dupes, they actively seek the elimination of Christianity and perhaps of Christians themselves. It's not Christians' religious liberties that are threatened, but the future of Christianity itself. Such paranoia feeds extremism; the belief that one is fighting for one's existence justifies abandoning normal standards of justice morality, making such arguments exceptionally dangerous.
This image is based on a World War II propaganda poster depicting the same hand sticking the same knife through the Bible. The only difference is that instead of "Godless Sodomites" on the wrist, the original poster has a swastika to symbolize the threat posed by the Nazis to Christianity. Few people at the time realized, or perhaps wanted to believe, the strong connections that existed between Nazism and German Christianity.