"I'll believe when I see," says Man.
"You'll see when you believe," says God.
It's an awfully seductive proposition, but take a step back for a moment: there are lots of 'gods', and most of them more-or-less say this.
So we ask ourselves: which is more probable? That among the thousand counterfeits--which operate by means unknown--there should be one true religion, and that it just happens to be the one you were born into? Or that it is the act of believing--and not the thing believed in--which creates the subjective experience?
Many try to argue that the near-universality of religious experience is evidence for God. Why animist visions, for example, should be viewed as evidence for Christianity remains somewhat unclear to me. Still, religious experience is a real--if subjective--phenomenon which must be accounted for.
But it occurs to me that this accounting is a far greater problem for the believer than the nonbeliever. The nonbeliever has merely to explain what mechanisms within the human psyche, what structures in the human brain, and what factors in human cultural evolution might have conspired to produce such phenomena. The believer, on the other hand, must produce similar explanations for everyone else's religious experience without also explaining away his own.