FROM ALVIN PLANTINGA, THE JOHN A. O'BRIEN PROFESSOR OF PHILOSOPHY AT THE UNIVERSITY OF NOTRE DAME: People have been giving arguments for the existence of God ever since the ancient world. These arguments haven’t necessarily had the intended effect in all cases: As someone once said, no one doubted the existence of God until the theologians starting proving it. Probably the most convincing theistic arguments start from the design of the universe or parts of it; the most recent of these design arguments revolves around the “fine-tuning” of the universe—the fact that various physical constants and parameters have to take on values that lie in an enormously small range if the universe is to be the sort of place in which life and consciousness can find a home.
People have also tried to disprove the existence of God; perhaps the most popular of these arguments would have to do with the evil the universe displays. Why would a wholly good, all-powerful, all-knowing Creator permit so much evil in the universe?
These arguments are interesting and important, and in my opinion, the arguments for the existence of God are better than the arguments against it. Perhaps these arguments really do show that it is more likely than not that there is such a person as God. I doubt very much, however, that any of these arguments taken singly or all of them taken together are strong enough to underwrite the way in which most believers in God actually do believe. Most believers believe much more strongly than these arguments warrant. At best, their conclusion would be that it is probable that there is such a person.
Does that mean that religious belief—in particular, belief in God—is intellectually substandard or second rate or irrational or unjustified or without warrant, or in some other way deplorable? People who want to claim that belief in God is irrational often seem to think their job is done if they succeed in showing that the theistic arguments don’t work. But are they right? Why think a believer in God needs good arguments if she is to be rational? There aren’t any good arguments for the existence of the past. As philosopher Bertrand Russell once pointed out, it’s possible that the whole world, together with all its wrinkled faces, apparent memories, rusted cars, crumbling mountains—it’s possible that it all popped into existence just 10 seconds ago. But no one believes that. Everyone believes in the existence of the past and does so in perfect rationality, even though there aren’t any good (non-question-begging) arguments for the past. In fact, what would be irrational would be to refuse to believe in the existence of the past on the grounds that there aren’t any good arguments for it.
Maybe the same goes for belief in God. The vast majority—maybe 90 percent—of the world’s population believes in God or something like God, and the alleged experts (in the scientific study of religion) now tell us that we are hard-wired to believe that way, just as we are hard-wired to believe in a past and in other persons. Most people who believe do not believe on the basis of arguments. They believe because they think they have experienced God in one way or another, felt God's presence, or because the thought that there is such a person as God just seems natural, right, acceptable.
So if that’s right, what is the function of arguments here?

Alvin Plantinga appears with Keith Ward, Owen Gingerich, William Lane Craig, Walter Sinnott-Armstrong, and Steven Weinberg in "Arguing God's Existence," the sixth episode in the Closer to Truth: Cosmos, Consciousness, God TV series, hosted and created by Robert Lawrence Kuhn. The series airs Thursdays on the PBS HD network and many other PBS stations. Every Friday, participants will share their views on the previous day's episode.