I can't think of a scenario where I would do this. Why would an atheist use religious dogma of any kind to make an argument against some other religious dogma? I guess you might be talking about the anti-Muslim sentiment growing in Western cultures and how an atheist might view Christians in a better light than Muslims. What interaction in your experience sparked this question?

There are many.

I do this. Mostly for the sake of argument, but also because I dislike unfair criticism (fair criticism with evidence etc is different) of fairly decent people taking whatever gets them through.

I've never seen this particular behavior first hand, but I'm not surprised by it. Our minds are fluid vessels of continuous information, and a thing we know today may escape us tomorrow, only to return again yet another day. But it's not an error particular to certain kinds of people, it's universal. It is a failure of the human mind to understand holistically the nature of reality and indeed its own capacity to sort out truth from fiction - even as the data piles up. Proof of this phenomenon can be seen all around us on a daily basis, including in the works of many of the most brilliant minds our species has ever known.

Only religion I was part of was the catholic... I had never defended the catholic but honest, I just don't argue.

That would make an atheist either confused or hypocritical? Offered as a question instead as an accusation. Too much mud-slinging around here.