The doge meme is popular because there's a specific, world-famous dog behind it. Trouble (right here in River City) is superbly memetic because of one man, Robert Preston, making the role practically a signature of his specific skill as a performer.
So if Christianity and Islam and other troublesome religions' beliefs are "simply memes", then what is the anchoring-point of those memes? It's a popular trope of Internet atheists to lump ALL religious lore into the general category of "faery-story"—which is itself something rather specific in truth, but the Internet atheist isn't too interested in distinguishing one type of fiction from another. "Faery-story" to them is simply reductive and pejorative, after the fashion of Dawkins's usage of "meme": "faery-story" might as well be a euphemistic way of saying "fancy lie".