The truth is that doubt strengthens religious faith only when one is prepared to yield to an overarching religious imperative--the need to believe--that cannot provide any rational answer to well-founded doubts but instead resorts to anti-rational formulas such as, "Lord I believe; help thou my unbelief."

I have always traced the end of my own faith to the frequent repetition of the story of Doubting Thomas, from the Gospel of John, by the nuns of my youth. For those unacquainted with the Bible (a startling high number of religious as well as nonreligious Americans, as Stephen Prothero points out in his Religious Literacy, the disciple Thomas refused to believe that Jesus had risen from the dead "except I shall see in his hands the print of the nails, and thrust my hand into his side."

Jesus complied, in those days of miracles relayed by reporters at second, third and
fourth hand, by showing himself to Thomas, and Thomas--after personally inspecting the wounds, fell to his knees and said, "My Lord and my God."

Jesus then admonished the doubting apostle, "Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet believed" (John 20: 24-29).

The point of this story, of course, was that we children were especially blessed because although we had not seen, we presumably believed. I concluded that if Thomas had not been visited by the risen Christ, he would have been amply justified in continuing to doubt a man's capacity to rise from the dead.

It took only one step further--a leap of doubt, if you will--for me to understand that if I were to have told anyone, in 1955, that I had seen and spoken with the risen Christ, no one (including the nuns and priests) would have believed me. They would, quite reasonably, have doubted my story and questioned the balance of my mind.

Only in the realm of religion is doubt sanctified by being dismissed even when the doubt is well justified by the laws of nature. This is why it is ridiculous to try to argue anyone out of religious doubt or, for that matter, religious belief. People who yearn to believe will believe and will find a way to suppress their doubts.

In the realm of science, by contrast, where various claims must be verified by repeated observation and experimentation, doubt is the engine of progress. Even though theologians tried to stigmatize the heliocentric theory of the solar system, they could not shut up Galileo and Copernicus, or the doubt they unleashed, by declaring, "We believe that God's earth is the center of the universe: Let God (and the Inquisition) help your unbelief."

Doubt about supernatural religion, like doubt about any ideology grounded not in evidence from the natural world but in metaphysics (Freudianism and Marxism come to mind), is really the voice of reason inside us. In the realm of religion, human beings frequently try to silence this voice, because it demands proof of a philosophy that can never be "proved" true but nevertheless satisfies the emotional longings of those who need faith to give meaning to their lives.