The blunt, simple, direct, straightforward answer is that Wiccans do not have First Amendment rights. Nor do Muslims, nor do Jews, nor do Native Americans, nor do Rastafarians, nor do any practitioners of any other religion other than Christianity. Whatever the First Amendment is about, whatever protections it extends in the federal Constitution, those were just for Christianity. Christianity has First Amendment rights under the federal Constitution, no other religion does.
Fischer is crazy, but it needs to be understood that he is not uniquely crazy; many, many, evangelicals believe the same thing, and are stoked in that belief by such as the fake historian David Barton.
You cannot reason with these people, because they don’t have a firm grip on reality. They must be defeated and driven back under their rocks.