You are mixing up Darwinism with Social Darwinism... It's not the same thing. Yes most atheists accept Darwinism ( but it is not a rule and you can be an atheist and suggest it happened in some other way, it's unlikely but you can) evolution is not the creed of atheism. Atheism has no creed. Liberals do not say the rich go to he'll and the poor are blessed. Liberals ( as in European Labour parties and mainstream liberals like Democrats in the US) generally say , " wow, the poor have it bad, because of the faulty system that allows the rich the profit regardless of a workers condition, the rich can help the poor... And if the rich don't want to is the failure to change is the same as saying no ) we can make a law that requires them to do so. " this is generally the ideology of liberals, they do not oppose you if you profit (ie if you are rich), they oppose you only if you profit, due to or in spite of someone suffering.
And if this a liberal vs conservative social values question like the original post suggests I think it is clear why some one who is religious would be conservative as it is written in the text that women are inferior, gays and lesbians are abominations, and the mainstream churches fight against abortion. But conservatisism is also often charecterized by exclusivism, and nationalism, and as I have said the religious culture centered around this is right, and everything else is wrong and evil and if you believe it you will burn in hell, this close mindedness often conicides with the close mindedness.