Religions have a lifetime. People don’t really like to think about this because we are always looking for certainty and religions have often offered us some measure of security in our certainty, and the idea that they necessarily grow and fall is not sympathetic to the mind.
But actually as we change so do they. From the advent of paintings that enabled cavemen and women to paint on walls the world around as they saw it, and apparently that world was all about animals and hunters, to the change from story-telling to written books and from written books to film. Each change, changes the religion because religions being created by the imagination are constantly worked upon by that imagination.
Religions always change as social structures change. Look at how Christmas has become embroiled with leaders showing their religious affiliation, people engaging in fiscal activity in the name of one of the poorest men who ever lived, the increased slaughter of animals (that hasn’t changed much) and the showering of affection upon close friends and family.
In fact as they change religions leave behind their creators, they become what we already are and fix themselves into our imaged ideas of what society is and how society functions. They say it is impossible to prove life is not a dream but that can only be because the dream is one we are making and we refuse to understand ourselves as different from how we imagine ourselves to be.