How do atheists explain the fine-tuned universe?

You know, I reject materialism, but the fine tune thing doesn't do much for me. I once heard a guy say if you lived in a wagon rut you' d say it was fine tuned to a wagon wheel. We are who we are because we live in this universe----I don't think God couldn't have made life out of something that had no matter or dimensions, or who knows what. I'll cop though to the fact that it always seems to be these old astrophysicists guys who convert based on this stuff, and they're all IQ of about 200, so, I can admit maybe it's over my head.