I'm an ex-catholic. I wouldn't say I left, though, it always seemed like a chore I had to do to make my religious relatives happy. But I went through CCD and got confirmed and all that jazz.
I'm just a boring old atheist I'm afraid. I used to call myself agnostic, because how can anyone know for sure god doesn't exist, right? But that seems like a copout, I'm not sure there isn't a teapot orbiting Saturn but I'm not agnostic about it, I very definitely believe there is no teapot orbiting saturn. If it turns out there is, I'll be wrong.
I find there's no reason for me to believe in a god. Or, another way I could say it is that the definition of "God" could work to describe the universe itself, but then you can't claim it's a benevolent god, as the universe just follows the laws of physics, it doesn't have morality.
Or, to put it another way, are you agnostic about Zeus? Buddha? Baal? How about peter pan? Was John Smith a prophet? Just because one story has been told for a very long time doesn't make it any more likely to be true, we've got countless examples of fiction that claim to be true.
That said, I've always found religious mythology interesting, including christian, so I'm pretty well versed on the catholic version of the bible.
I'm not preachy about it though, but since you asked I figured I'd answer.