I'm going to second JoshuaZ here. There's a lot of disagreement among theists about what the best arguments for theism are. I'd rather not try to represent any particular argument as the best one available for theism, because I can't think of anything that theists would universally agree on as a good argument, and I don't endorse any of the arguments myself.

I would say that most atheists are at least exposed to arguments that apologists of some standing, such as C.S. Lewis or William Lane Craig, actually use.