Oh no, trust me, I'm an atheist. I spent many years calling myself an agnostic - the 'ag' is less off-putting for folks and my basic attitude is that I don't care. (The existence or non-existence of higher beings simply doesn't factor into my moral/philosophical/physical/whatever framework.)
The term you're looking for is "Apatheist". It means exactly what you're saying, and it actually sounds legitimate enough for people who aren't paying close attention.
A close second is "Frisbeetarian"; if you say it quickly it sounds a lot like "Presbyterian", but it's the belief that when we die, our souls go up and get stuck on the roof.
Back in the day, I used to listen to a band called "Seventh Angel". I think they might qualify as Christian Death Metal, fistful...
-BP