How to Know Which Religion is True. Depending on how one defines religion, there are thousands of religions in the world. Given such religious diversity, how can any one religion claim to know the truth? Nothing proposed so far has helped us settle which of these religions, if any, are true until now. Former minister-turned-atheist John Loftus thinks we would all be better off if we reviewed any religion including our own with the informed skepticism of an outsider. For this reason, he has devised the outsider test for faith. He describes it as a variation of the Golden Rule Do unto your faith what you do to other faiths.