It's not uncommon for atheists to trot out the argument that wars and murders have been carried out in the name of religion. Now, this is not a good reason to be an atheist. The lack of evidence for god, that is a reason to be an atheist. The fact that of all the explanations for the existence of the universe, "God did it" is the least feasible - that's a good reason not to believe in god. But the shitty stuff done in His name - sorry, no. That's not a good reason. It's just sulking.
The crux of this argument was that the religious sorts were claiming that it was unfair to blame a religion for the nastier things done in its name. When it was pointed out by others (not me) that war and murder on religious grounds has been commonplace, and that no such thing has been done in the name of atheism, they began to flounder. The Muslim dropped out of the conversation, after asserting that Soviet purges were carried out for the purposes of spreading atheism, but the Christian chappy struggled on for a bit.
His final point was that if nothing bad has been done in the name of atheism, nothing good had been done in its name either.
And there, right there, we find the fundamental misunderstanding of the religious mind. Because, you see, many religious people view atheism as a subsitute for religion. And it's not. It is the absence of religion.
Let's say you are a Christian. It's feasible that you would go out and do certain things - good or bad, laudable or execrable - in the name of Christianity. But you wouldn't go out and do things in the name of not being a Muslim, of not being a Hindu.
So why then would an atheist do anything in the name of not believing in god?