I may be going out on a limb here, but I'm going to say Christianity is popular. After all, who can think of a manger without thinking of Jesus?
But is it popular because it's right? Or does Jesus just have one hell of a PR team?
pr is all about selling. Get people to think what you think--about a product or an idea--and stop any criticism or critical thinking the best you can. With television ads, Nike slam-dunks criticism for making their shoes with third-world child labor.