Phenomena which some people can't explain, and someone willing to exploit that ignorance, offering their own explanations, and with ways to gain something over the unknowing people. Magicians, con artists, and scholars can take advantage. Back in time most people relied on someone else to read any writing, so anything can be claimed as "written", unchallenged. Production of rituals and rules to 'belong'. Production of 'writings', to set directions and attitudes and agendas. Acolytes, zealots, and stakeholders promote and solicit others for interest to join and pay. It becomes a business, and goes professional. Premises, uniforms, literature, lobbyists, and so on. Thats a simplistic explanation. Of course it is more tricky than that.
Anyone can start their own 'religion'; just look at Scientology, a laugh.
Pretty accurate but I read the OP as trying to understand why someone starts to believe in religion.
What's gives birth to religious beliefs?
Religious beliefs start for any number of reasons.
* a need to feel wanted or accepted.
* a way to explain unfavorable circumstances and events.
* a need for guidance or discipline.
* a traditional alignment with someone who is religious.
Plus any other reason a person might decide.
There are commonalities in religions which have common defining mental states.
* restrictive viewpoints.
* a need for punishment and reward.
* a need to exist (in some way intact) past death.
* a separation from natural reality (many religious people believe humans are not animals).
* a need for the unity of a society.
* a reason/excuse for lack of self-control, unexplained phenomenon or dreams/fantasies.
* a way to escape the reality which is before them.
In exploring what gives birth to religious beliefs one must also explore why some people
do not adopt religious beliefs.
Examining only one side of it gives a lop-sided, biased view of the whole.
Belief may or may not be reality but reality is
always reality.
