Those are all examples of shit that doesn't matter.
This is a valid point. It always sucks when people use religion to justify public policy decisions that you don't agree with. The thing is, the way people react to others' beliefs is OFTEN not just a complaint about a specific issue like this. I don't know if you've noticed, but often when people talk about Christianity (or w/e), it's not just in the sense of public policy, but a reaction to the fact that they believe in a SKY WIZARD!!!
I guess I'm reacting mostly to the fact that many people lack of respect for each others' personal beliefs that don't affect them. Does it matter if people literally think a snake tempted adam and eve, etc? No, it matters that many Christians don't believe homosexual couples have the right to marry.
So why isn't the discussion of things related just to those issues? I don't know, people are assholes I guess. Everyone reacts too strongly to unrelated flaws of people's beliefs.
I hope I'm making sense, and just for the record I consider myself agnostic (and as I've gotten older I've shied more and more away from belief in any sort of god).