Here's an attempt by Jeffrey Goldberg to figure out which religion is the weirdest. He can't:
What Mormons suffer from more than any other major religion is proximity. The foundation stories of Mormonism took place in the age of skeptical journalism, and they took place in the U.S. Most Christians believe in a Second Coming. Mormons believe the Second Coming will be in Missouri. Many Muslims believe that Muhammad ascended to heaven from Jerusalem on a winged animal, which has the ring of something mystical and transcendent. If Muhammad had departed for heaven from Tenafly, New Jersey, well, that would open up Islam to some level of derision.
He's right, of course. Time makes everything look less ridiculous. I have a few non-doctrinal yardsticks to think about the question of how legitimate a religion is. 1. Does it have secret, sacred places that are sealed off from outsiders? 2. Is there some kind of esoteric teaching involved known only to those high up in the faith? 3. Is it easy to leave the church, i.e. is apostasy without serious consequences? 4. Does it enforce tithing effectively?