In 2001, a poll revealed that only 17% agreed that "My religion is the only true religion" and most of them were fundamentalist Christians. 78% could not agree with that exclusive statement. Along these same lines, fundamentalists believe that the Bible is the actual word of God, to be taken literally, word for word. In 2002, the number of Americans who believed in biblical literalism had declined to 27%, down from 65% forty years earlier. Notice how closely these numbers coincide with the CBS poll that showed that 82% thought Congress and the President went too far in intervening in the personal matter of Terri Schiavo's death, or with the 75% in the Time poll that thought Congress should not intervene in the matter.
If you believe that your religion is the only true religion, and that all others are destined for eternal damnation, you are much more inclined to impose your religious beliefs on others through political action. Conversely, if you believe that other religions, and other believers, may hold alternative keys to salvation, you are much more inclined to tolerate the religious views of others, and to insist on religious tolerance in law. In the 17th Century, a woman by the name of Anne Hutchison was tried in the Massachusetts Bay Colony as a heretic and exiled. She and her family struck out into Rhode Island and eventually New York in search of religious freedom. Eventually, her descendants were elected President of the United States seven times. How ironic that the last one was George W. Bush.