LDB,
That was a great post, and I'm upset (from a distance, of course) that you have to put up with pushy religious people at work.
I note the contrast between the kind of Christian your boss is (in-your-face) and the kind of non-Christians your co-workers are (careful to not offend). Obviously not all Christians are like your boss.
However, certain brands of religion (including certain brands of Christianity) are both narrow-minded and evangelical / expansionistic, believing that THEIR god must be followed and everyone else is on a slippery road to perdition of some kind.
It's offensive. An atheist, when asked, will explain his or her views, perhaps in very blunt terms, but will not claim some of moral superiority for himself or condemn believers as inferior merely for having a belief.