I was a gnostic atheist but became agnostic atheist. I am very much against organised religions, but I believe anyone should be able to believe in anything they want. At the conditions that they do not try to shove it down the throat of others or hurt anyone with their beliefs.
On God, the thing that made me change my mind is that you cannot clearly define what God is (the definition varies from person to person), so you can't be certain that it does or doesn't exist. Is God a bearded dude in the sky? Nature ? The Universe ?
As far as I'm concerned, if God exists, it would be very pretentious to think that it gives a crap about us, and even then, it would probably not be benevolent. Especially when you consider the amount of suffering happening on earth everyday.