To doubt atheism? I'm not sure (hehe). It's the sort of question which it's difficult to imagine we'll ever have an answer to. If you define "God" as "the reason why there's something rather than nothing", then you've not said much else about God (see auntysarah's comment, above), and indeed, I don't think you've explained very much. If you say "the Christian God, who was incarnate as Jesus, answers prayers, etc. etc. is the reason why there's something rather than nothing", then one might equally ask why there's that God rather than nothing, or indeed, another sort of God.