I am totally in the closet on Facebook but one of my Facebook friends who is 18 put a caption under her profile that said "fuck your religion". But I don't think you can have captions under your profile any longer and I don't think it gets any more offensive then that.
That's kind of like having a sign on your front door that instead of saying "no solicitation" it says "fuck your religion" lol. That's just too much but she is a funny one (the good kind of funny).
First off, I have two facebook accounts. One is work, my kid's friends, family, Xian friends, everybody but the really rude fuckers. I call it my PG-13 facebook page. Its not PC, but its pretty tame. 800+ friends.
On my NC-17 page, I speak my mind much more freely. Less than 100 friends.
I didn't proselytize much (in my mind) when I was a Xian. I ignore most Christian comments and posts, but get in my face and you will get it with both barrels. Occasionally something will rub me the wrong way and I will say something causing a shitslide. I will slam those who post intolerant bullshit on either account.
There is a time and a place for everything. I don't make a secret about being an atheist, but I don't walk around rubbing people's faces in it. I'm happy to have conversations with people if they are civil. I do post atheist links and articles on both accounts, but I don't overrun them. I'm not out to deconvert the world. Yet.
I'm sorry for your loss of your friend but at least it is a good sign that intelligence is poking its tender head into your Facebook.