Most personally convincing reasons you don't believe.

[emjay]

What are your most convincing reasons for not believing in god? I don't mean convincing to other people (necessarily) but convincing to yourself... what reasons stop you going back (if you are an ex-theist) even if you wanted to?

I'm an ex-Christian so I have baggage and I admit that very occasionally I am tempted back but one of the reasons that prevents me is simply the fact of contradictions in the Bible: if there are contradictions it can't be infallible, and if it's not infallible but only 'inspired' then how can you trust any of it (or know what to trust)? Ultimately it is that reason that stops me in my tracks if I'm ever tempted to read the Bible again... I literally cannot get past the first few pages of Genesis without thinking 'this is silly' even if I actually want to go back to Christianity.

I'd love to hear what other core reasons people have for not believing... reasons that act like mental blocks to ever returning. Ashamedly I do have doubts from time to time and so am not 100% certain like Rob, but I'd like to be, and I think having a few more core reasons (rather than superficial/semantic reasons) would help