"From what I've gathered, they've never really 'doodled' 
     anything that could remotely resemble a religion..."

Maybe that's policy now, but it hasn't always been. They've done easter: http://www.google.com/doodles/happy-easter-2000

In fact, having already done Easter was part of their response to this "controversy" -- there were two subjects for the same day, so they picked the one they hadn't already featured.