The most common argument given by atheists today for not believing is the 'lack of evidence' argument. The argument is, essentially, that since there exists no positive evidence of God's existence there is no good reason to believe in him. This argument has some problems.
If God exists, would we expect to see anything other than what we do in fact see? Is there any reason that we should expect him to, perhaps, materialize and reveal himself in some visible or audible form regularly? Or perhaps to have left a signature of 'Yaweh' engraved in every stone? I don't believe there is any reason we should expect evidence of this sort. Further, if God exists and is the creator of the world then everything--every bird, every tree, every star, every galaxy, every human and every atom-- is evidence of his existence. With this being the case the statement that 'There is no evidence for God' becomes quite meaningless. It's merely a re-statement of disbelief in other terms. If He exists then all is evidence. If he doesn't then there is no evidence. Whether or not something constitutes evidence depends on whether he exists.
"Well, you could make the same argument for The Flying Spaghetti Monster!"
If you define 'The Flying Spaghetti Monster' to be the transcendent, immaterial, atemporal being that created the cosmos then, yes, that's true. But all you've done in that case is given God a new and peculiar moniker. God--even if he didn't exist, but merely in conception--is not a thing amongst things. He is not even an idea like any other idea. He is a category unto himself which is why analogies to unicorns, Santa Clause, FSM or Abraham Lincoln don't work.
As you can see the argument falls flat on its face. And this is before even discussing the fact that, at least for the Christian faith, all manner of geological, historical, astronomical and physical evidence can be marshalled in favor of its specific truth claims, while there exists no sorts of evidence that controverts them, or at least that nothing that is irreconcilable with them.