This list is just what I am aware of, and there are certainly many more about which I am ignorant, to my loss. Why am I ignorant of them though? Undoubtedly there are some religions of which no remnants have survived, their beliefs and rituals completely lost to the past, others will have been subsumed and aggressively curtailed by other, more successful faiths, and yet more still will eke out a survival with a small but dedicated following, isolated from other people.
Religions evolve over time, they spawn sister species which become competitors and, just like with biological evolution, sometimes they out-evolve others leading to inevitable extinctions. In modern times this isn't always such a bad thing, the big religions adapt to the changing times - far more Christian churches, for example, are tolerant of women's rights than there were at the beginning of the 20th century. In ancient times, however, it may not have been such a boon.
One of the earliest comments on Darwin's theory of evolution by natural selection was made by Herbert Spencer, a polymath scientist, and Darwin actually incorporated the comment into the fifth edition of his book On the Origin of Species... It was 'survival of the fittest,' long since one of the most misunderstood terms in biology, after evolution itself. Spencer and Darwin used the term not to imply the physically fit, the most intelligent, the fleetest of foot, but the individual most fit to the environment in which it lived.
Religions have long been subject to this concept and older religions have tended to be forced to the outskirts of society by ones which appear more suited to the environment. Unlike biological evolution though, religions had a hand in shaping the environment. When the Emperor Constantine converted to Christianity and later Emperors of Rome eventually outlawed other religions Christianity had created an arena where it was the fittest to survive, because following other religions would lead to great sanctions.
I don't have as strong a knowledge of how it happened elsewhere around the world, but I would imagine that Hinduism in India underwent a similar power struggle with other local religions in its early days, as well as Islam in the Middle East. Because it is the survival of the fittest, not the survival of the nicest. A certain aggression and violence is inherently part of religions' history, as it is a large part of the way a religion will get a significant following in darker times.
In modern times there are two major routes that a church can take; they can either move with the times or they can stubbornly stick to their old methods and refuse to budge. Middle Eastern Islam and Roman Catholicism are two different examples of this second group, both stubbornly clinging to an old way of doing things; in one case in a moderate way, in the other a medieval attitude.
All of the dominant religions have had to trample across hundreds of smaller traditions on the way. Now that they're up against a group who are proving that they can push back effectively they are beginning to panic.
Here endeth the rant...
As an unrelated aside:
Congratulations to Jessica Ahlquist. We're all evil little things with you!
