For believers anybody can but should not utter profanities. Atheists are not exempted.

It is pretty easy to piss off believers using what they deem as profane, but what does an Agnostic or Atheist consider "profane"?

I don't know but it doesn't prevent me from trying, HARD!

Why conundrum? I am profane every day with religious brainwashed morons in that at best I am irreverent with their beliefs and at worst disrespectful. And I am a total and complete 100% non believer.

Profane the idea of science. "a: Knowledge or a system of knowledge covering general truths or the operation of general laws especially as obtained and tested through scientific method
b: such knowledge or such a system of knowledge concerned with the physical world and its phenomena : NATURAL SCIENCE" Merriam-Webster

One cannot, now tell the believers and not try not to lose your head about it.

Profane
verb
treat (something sacred) with irreverence or disrespect.

Your neighbor has a sacred statue of Harry Potter god, you sneak over and piss on the statue.

One of the challenges to secularists is dealing with the linguistic remnants of religion. Enormous numbers of words and phrases that are common parlance must either be discarded or redefined for a secular context. This confusion is commonly used by religionists as a segue to their proselytizing spiel.

The word profane loses its metaphysical implication, which was always absurd anyway. It becomes synonymous with: vulgar, abusive, indecent, obscene.