But that's just identifying your old belief.
How are you a protestant atheist besides the fact you used to be a protestant?
IS there a difference between a Protestant atheist and an Islamic atheist, besides having different upbringings?
An atheist is just an atheist; a non-believer who doesn't believe in gods.
Anything besides that has nothing to do with you being an atheist and is a descent into personal belief.
Christianity isnt just a religion. Not really. It is a totalogy. It is a belief system that prescribes methods for various ways of doing almost anything.
Christianity has had an answer for everything for 2000 years. As such it has influenced nearly everything we do, even the most secular among us. So much so that even Christopher Hitchens referred to himself as a protestant atheist.
Having given up the belief in a God that killed himself becuae he couldn't change his own rules, I'm still a member of a culture that has been totally subjected to Christian influence for most of the last two millenia.