For my atheist friends, a (silly) question of etiquette?

It's grammatically correct to spell "atheist" and "agnostic" lower case, while names of religions and deities are capitalized. It's not an issue of etiquette, but of grammar.

LOL you are joking about the tendency of Fellow Pious Christians to Capitalise Nearly Everything, right?

I think you should look for advice in a style guide (eg Chicago Manual of Style). Actually, take a look at a few.

If you find contradictory information, make a decision and be consistent.

I capitalize names, not groups. To me, an individual is more important then the group that they belong to.

For example .... "Its a commonly accepted fact that *christians* believe in the divinity of *Jesus*."

Of course, even if you don't capitalize my name, I won't care. :)

In general, we capitalize organized groups but not generalizaions. We would capitalize the Freemaons because they are organized but not car-drivers because they aren't. Atheists are not organized and so grammarically we would not capitalize it. I tend to choose capitalization by context, if I am referring to it as an ism, I do but as and ist, I tend not to.

i never capitalize anything... too many buttons

i dont think any of us atheists will mind, sweet to ask though

but its uppercase technically as an organization just not in general.

Atheism is a religion, with a set beleif of having no beleifs. that means it gets the same treatment as all the others, which for me is lowercase, but for others is usually with a capital letter.

Agnostic, on the other hand, is not a true religion, therefore gets no cap. I am agnostic because I have no set beleifs, therefore do not follow a religion.

atheism is far from religion.but should be in capitals after all a very important word when we speak about religion

lowercase... unless it's at the beginning of a sentence.

lowercase is grammatically correct, it has nothing to do with etiquette

I don't capitalize it, as it's not a religion. I don't get offended either way, though. :-P