I'll also post something like that every once in a while, but honestly, most of my tangling with Xtians on facebook is in reaction to something they post. I have a sister and a friend who post religious stuff on occasion; I'll react to it, then some friend of theirs will take huge offence. "How dare you insult my god like that?" They never win. I got one dude to admit he was okay with god being a baby killer. That, after a dozen ad hominem attacks.

I particularly like engaging Xtians on an open and public forum, cuz I'm imagining all the silent lurkers listening in...

the truth hurts especially when it makes you look a twat

Well at first glance, it just looks "angry." And, it looks too long to read. I bet most of them don't even read it and just dismiss it immediately. And if they do read it, then they might have to go to their pastor and ask what the proper response is. And he'll give them some mumbo jumbo bible passage that's supposed to be the perfect counter argument. Either way, they will not be educated, and you'll just be the bad guy. Sadly, that's how this mostly works out in my opinion. And that's a shame, because I think it's a really good question for Christians!

I'm in several Facebook groups where I feel free to share without fear of familial backlash.
Why Facebook is not for older people........Once my mother was offended by a post a commented (Dear Sharon, please stop sharing this stuff, it's embarrassing. What if my Sunday school class sees and thinks you worship the devil - Love Mom) She typed it out like a letter with the formal greetings and such, I called her to explain that despite the fact that it's showing in her news feed does not mean that her Sunday school can see it and explained how Facebook works in general, then I told her what unfriending and blocking was, and how my friends had been laughing at her embarrassing comment to my post that could have been sent privately, as if I was a scolded child.....then I blocked my mother.

I will have to try this one and then get back to you.