Where does altruism come from? These atheists should be able to find hundreds of examples of non-religious societies thriving with spontaneous altruism.
Do they get the irony that they live in a Christian nation, founded on godliness and Christian doctrine?
The only logical end of unfettered, honest atheism is nihilism. These folks need to read Nietzsche to see the futility and meaninglessness of their rantings.