I'm fearful of sounding like a redditroll, but Hitchens handles this particular topic well. He asks people to name a single moral act believers can do that nonbelievers cannot do. Then, when no one has an answer, he asks a corollary; name a single act of evil done entirely in god's name.
With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion.
-- Steven Weinberg
That attitude makes me uneasy. Atheists are tempted to dismiss religion and sit back, confident in our superior rationality. But what we should do is try to learn even more from theist errors. The errors are not just limited to the obvious (to us) errors like faith in the supernatural. There's also obedience to authority. The Milgram Experiments show that plenty of good people will do evil in certain circumstances.
I don't think Hitchens handles the topic well, at least not as you present it.
In the first comparison we compare two groups, we find both with the ability to do moral acts. Next we compare the two groups again, but this time we are surprised when we find both groups are capable of non-moral acts. Also, we jump from a simple comparison of believers and non-believers to the use of god's name.
The point just doesn't say much more than, "people are capable of good and evil". A religious person would only become troubled that evil people are misappropriating their belief system to back their evil acts. i.e. Hitchens point will not faze a religious person.
A better response would be to show in the positive that a similar morality to Christianity can be built from a few well reasoned assumptions. This would address the GP's wish to show that morality is not dependent on a religious system. It is important to remember, from a religious persons perspective morality is defined by God. Responding with annoyance gets one nothing and shows that a person may be vulnerable to the same shortsightedness.
I suppose it depends where in the conversation you are. Sometimes you have to start from scratch with people who believe religion has a monopoly on morality. If the conversation doesn't require such basics, then by all means jump forward.
