They change over time as their environment changes. They mutate, in that they change a few key beliefs, and evolve into a different 'species', sorry 'religion'. They start out very similar to the parent organisation, but get to the stage where they can no longer reproduce with them.
The new environment can take a variety of forms - it could involve transplantation to a new country, or the arrival of ideas from another culture, or just another charismatic preacher.
Those that adapt successfully, thrive and grow.
Those which fail to adapt wither, and become extinct.
But the new sect is never a completely 'clean sheet' invention - it is just a modification of the generation that went before, and you can easily trace it's roots.
Sound familiar?
Which Religion?
If religious claims were as obviously correct as the claim that the sun exists, everyone would quickly agree. That’s not the world we live in.
Even if believers say that religious truth isn’t clearly perceived but only dimly so (one wonders why god(s) couldn’t clearly convey the message, but ignore that for now), shouldn’t religions be converging? In this scenario, religions worldwide would be sifting clues for evidence of the supernatural. Bits of evidence from religious seekers worldwide could gradually be collected, like jigsaw puzzle pieces. Religions would converge. But, of course, that’s not at all what we see.
The tree of world religions above makes clear that religion is doing the opposite—diverging instead of converging. Christianity has fragmented and morphed over time as new cults and sects form. We see that same fertility in other religions. The only commonality we see across religions is humans’ interest in the supernatural.
This disconnect between religion and the reality that would ground it makes plain that all religions are just man-made institutions.
New Churches
Christianity alone creates two new denominations per day, but it’s a global phenomenon, illustrated in the tree of world religions.