Questioning?Is there reasonable evidence that God exists? If not, frankly there's no reason to believe it!

Peter Kreeft, a philosophy professor who is also an excellent and engaging writer, has compiled a list of 20 reasons to believe God exists:
Twenty Arguments For The Existence Of God

This list is actually copied verbatim from one of his books. Note that these arguments are "religion neutral", that is, though Kreeft is Christian he is not arguing for the Christian God per se, just that God (of some nature) exists. Naturally, some arguments are stronger than others (in particular #17 is intended, I think, at least partially tongue-in-cheek) but some of those that I find particularly strong are:

Being a former atheist, I decided to investigate the evidence for myself for the first time. Are you willing to honestly take a first step, an unsure but hopeful step of 'faith' today and do the same? After all you've got nothing to lose. I did just that, and eventually concluded could no longer hold onto my atheistic beliefs any longer.

(For more resources, see the Existence of God section of Jesus: Fact or Fiction, or any of the links in the Links sidebar on the right hand side of this page.)