The same cognitive bias that leads pagans to believe in witches and multiple gods leads theists to believe in God. Indeed, once the explanatory principle--to ascribe worldly events that bear on human well-being to the intentions and powers of unseen spirits, when no actual person is observed to have caused them--is admitted, it is hard to deny that the evidence for polytheism and spiritualism of all heretical varieties is exactly on a par with the evidence for theism (("If God is Dead, Is Everything Permitted," in Philosophers without Gods, ed. Louise Antony ,p. 227).
Anderson recounts her experience at the summer fair in Ann Arbor, Michigan where various religious groups have booths from which to propagate their faith.
Along one street one finds booths of Catholics, Baptists, Calvinists, Christian Orthodox ... Muslims, Hindus, Buddhists, Baha'i, Mormons, Christian Scientists, Jehovah's Witnesses, Jews for Jesus, Wiccans, Scientologists, New Age believers--representatives of nearly every religion that has a significant presence in the United States. The believers in each booth offer evidence of exactly the same kind to advance their religion. Every faith points to its own holy texts and oral traditions, its spiritual experiences, miracles and prophets, its testimonies of wayward lives turned around by conversion, rebirth of faith, or return to the church. Each religion takes these experiences and reports them as conclusive evidence for its peculiar set of beliefs.
... [I] am always struck by the fact that they are staffed by people who are convinced of their own revelations and miracles, while most so readily disparage the revelations and miracles of other faiths. To a mainstream Christian, Jew, or Muslim, nothing is more obvious than that founders and prophets of other religions, such as Joseph Smith, the Rev. Moon, Mary Baker Eddy, and L. Ron Hubbard, are either frauds or delusional, their purported miracles or cures tricks played upon a credulous audience, their prophecies false, their metaphysics absurd. To me, nothing is more obvious than that the evidence cited on behalf of Christianity, Judaism, and Islam is of exactly the same type and quality cited on behalf of such despised religons. Indeed, it is on a par with the evidence for Zeus, Baal, Thor, and other long-abandoned gods, who are now considered ridiculous by nearly everyone (Ibid., pp. 226-27).
Man seems to be a religious animal and will look for something beyond the natural world to explain what he does not understand. When one becomes a true believer in a particular religion, other contradictory religions are written off as delusional. Yet, if one applied the same standards to his own religion as he is applying to the ones he rejects, he would reject his own as well (This is essentially "The Outsider Test of Faith" popularized by John Loftus). As Robert Heinlein quipped: One man's religion is another man's belly laugh.
When I was an evangelical Christian, I remember wondering how any intelligent person could believe the teaching of Mormonism. Yet, I encountered intelligent lawyers, doctors, and other professionals who were Mormons. This was always something of a mystery to me. I concluded that they must believe, if they really do, without thinking much about it. They must be Mormons because their families have been Mormons for generations. In other words, they believed not based on an impartial examination of the evidence but because of societal and cultural influences. But when I applied the same logic to my own belief system, I looked for excuses as to why my beliefs were rational and not merely due to cultural considerations. Eventually, I came to the conclusion that it is no more logical to believe that God appeared to Moses than it was to believe he appeared to Joseph Smith (or Muhammad or any of the other thousands who have claimed to hear directly from God).