I was having lunch with an Atheist today...

[robvalue]

Quickest way to defeat the moral argument is to ask him why he doesn't follow his own moral guidelines and stone people to death for working on a Sunday and so forth. Or why the Ten Commandments don't even mention theft, slavery, murder or rape.

So called objective morality isn't morality at all, it's amoral, just following rules. But by not following it completely, your friend is making their own moral judgements about each of these rules. They do the ones they think are moral, and ignore the ones they think are not (or pretend the bible doesn't say it). So all they are doing is using their own morality, and using the bible as justification when it's convenient.

Of course, your friend may know better than God what is moral, and knows what corrections he is planning to make to the book but hasn't got around to.