However, the commenters have got me thinking about the basis of the successes of major religions - by "success" I mean "attained Major status", with an undercurrent of "by eliminating or displacing other belief systems".
The fundamental observation to this thought process is by Alon Levy, a commenter, in response to the question "Will Muslim and Christian fundamentalists "discover" that they can work together?":
They already have, to some extent. Interfaith meetings of Jews, Muslims, and Christians have turned into gay-bashing events in which all participants agree to fight the common enemies that are science, homosexuality, liberalism, and free thought.
So the major religions share a hate-on for certain things - like science and free thought. Rather than a consequence of religion, perhaps these attitudes are a cause of those religions. If human minds are particularly open to concepts centered on supernatural authority and exclusion of "the other", an up-and-coming religion could take advantage of these traits and incorporate them into theology. This doesn't have to be the recognition of particular human weaknesses by a cynical, intelligent, charismatic leader - such attitudes can accrue to a religion gradually, through a selective process as successful religions add them and failling religions don't.
There's probably an irony in there somewhere.