Stephen Fry once said:

"It's now very common to hear people say, "I'm rather offended by that", as if that gives them certain rights. It's no more than a whine. It has no meaning, it has no purpose, it has no reason to be respected as a phrase. "I'm offended by that." Well, so fucking what?"

There's a phrase for your Facebook page. I don't think you can be an atheist without causing some religious people some offence. I don't see it as a bad thing though. I personally just try and keep calm and rational, often in the face of fury. We're doing nothing wrong, plus we'll always have facts on our side. Maybe the key is to try and make these people see that you're not an atheist simply to cause them, or their God, offence. Rather, you simply think it's ridiculous.

Sounds so simple on paper (or on the computer screen, as the case may be).