It keeps a limited number of people on an even keel, through guilt and fear of comitting sin or ending up in hell. But most people use it as a crutch, because they and we don’t have all the answers as to why things are the way they are. Some people cannot live without having some kind of explanation for the way things are, even if that reason is a fairy tale, or is false.
For another group of people, religion gives them a validation for their bad behavior, because if they just “repent” or say a few “hail mary’s” then every bad thing that they do is completely forgiven.
Another group uses their own particular brand of religions and it’s rhetoric to justify horrific deeds and actions towards/against other people and animals.
For a smaller group of people, saying that they are religious helps them to fit in with most of the rest of society who claims to believe in religion or a higher power and it keeps them from being ostracized, browbeaten or thrown in jail, if they fail to believe (or act like they believe) in a particular religion.
A lot of people enjoy believing in religion, because it absolves them of having to figure things out for themselves, to look for real reasons for why things happen (including the fact that there may be no actual “reason” but that things are just a series of chain reactions) and by hiding behind the word faith (which means absolute belief without quesion) because it absolves them of having to try to prove or dis-prove anything. It’s much easier, and probably a lot more pleasant, to blindlly go along with what some heirarchical bigwig has told you than it is to think for yourself. And if you allow yourself to have “faith” then you never even have to think about whether it’s real or not real. It makes life a lot easier to deal with.
Some people enjoy the social aspect of religion. It’s a lot easier to be exactly like everyone else. If you’re different, you will stand out like a sore thumb, are likely to be called names, be ostracized and possibly ridiculed and bullied or even killed.
And some people enjoy the pomp and circumstance and rituals of religion, even if they don’t have any idea what the religion actually stands for.
And some people, never stopped believing in magical pink unicorns and Santa Claus. Religion is another manifestation of “magical beliefs.”
And some people only come for the covered dish lunches.
I don’t doubt that people actually really do believe in religion. But I think those same people, if they were born in China or Africa or the North pole would still believe in some sort of religion, but it wouldn’t be the one that they were born into (as of today). People tend to believe what they are told by their families and communities. It depends upon where you were born and what you were told by your family and how strong the desire of the community to make sure you believe the same way that the majority of any particular community believes. If people were told nothing about faith and religion and then were made to wait until they were of age to study all religions and to pick one or none at all (with no pressure by family or community) people wouldn’t be so quick to fall into lockstep with the majority of people around them. There would still be people who believe in faith, but there would be lots and lots of people choosing all sorts of different ideas, rather than just going along with the one that is prevalent in their community or family.