Agreed. I think this is a cultural thing rather than a truly rational thing. I was brought up as an atheist, and would still describe myself as such, but I wouldn't give a zero probability to the simulation argument, or to Tipler's Omega Point, or whatever (I wouldn't give a high probability to either - and Tipler's work post about 1994 has been obvious ravings) and I can imagine other scenarios in which something we might call God might exist. I don't see myself changing my mind on the theism question, but I don't consider it a closed one.