Ha...good for them.
I like to see the self-satisfied xtians get their feathers ruffled.
How is mocking someone for being religious more acceptable than a religious person chastising someone for not being religious?
Plus, you have to question the motives of someone who uses shock value to further their cause. They want to deliberately provoke a response so they can then divert attention from their actual position by screaming "look at these horrible Christians! Don't notice how stupid and ridiculous and over the top I am - they are the ones!!" If your cause is a legit one, if being atheist is so much better than being a christian, then explan why. If you can't do that, then maybe your cause is fucked up?
I have this same issue with ANY extremist organization. Getting pubicity does not legitimize your cause - it only gives others a basis to mock you.