Look up "Jo Nesbo on religion " for a remarkable quote on religion. (I'd post it myself if I were more cell phone savvy)

Great question to which I have given much thought. At first I was reluctant to admit religion had anything worthwhile to attract followers. I have since changed my mind. Religion began gradually as the first human mind evolved. We see evidence of this in Neanderthal burial sites. Of course, leaders and shamens used it for mental and physical control when clans became too large for a few people to control the growing communities. With a believe in a deity or two, there was always something watching and controlling. When concerted action was needed, such as in hunting or war, if it was always deity approved; it was easier to organize and control diverse communities with the aid of watch-dog deities. So, in the run, deities did help control and organize human society. They also answer questions in the absence of science and were a help in growing societies. I have no doubt that individuals used religion for their own benefit then as they do now. Civil laws and religious laws are meant to control behavior, and they do that with great success, but some time to the disadvantage of those who follow blindly without question or input. Unfortunately, some religious leaders become so possessed with their newfound power that their leadership actually becomes a treat to followers, who might be encouraged to commit suicide or perform acts of inhuman cruelty. So, in the long run, religion has both helped society and harmed society. The policies of both religious and political leaders must always be questioned. When leaders are effective, both in their religious and political influence, they become especially powerful and potentially dangerous to followers and enemies alike. Thus, the separation of church and state becomes even more important to government. Religion has made sense in the past and still does so to a certain extent, but the dangers inherent in it can be a grave threat to individuals and society. In some societies, as freethought and education becomes more prevelant, religion is on the wane. Humanity no longer needs it to stop humans from raping, theft and murder, and to control our very thoughts as in the past. Religion is gradually being replaced by science and reason.

This is an interesting response.
[bigthink.com]

Control

It's something to blame if something goes wrong. If something like a family member gets cancer then people turn to it for hope. Also it's taught through generations. Kids are taught religion before they can walk.

Before philosophy and subsequently the basis of the scientific method, people superimposed human characteristics to natural phenomena they otherwise had no way to explain....thats where it started......then at some point the tradition(s) of metaphysical/spiritual constructs became a power trip.

The first gods were described on cave walls to explain thunder and lightning. So the first answer as to why is that it's in our nature to create answers where they cannot be found. The cave men weren't trying to control anyone, they were simply scared shitless of the loud boom and flash. Enter human flaws again incorrectly linking correlation and causality and enter the idea of an interactive entity, with appeasement. "If I kill a goat and leave it on a big rock, the lightning doesn't seem as bad." At that point it was off to the races. If there's an interactive role with your unknown all-powerful entity along comes mortal judgment, "my goat was bigger than yours". Now all of a sudden there's a hierarchical structure with someone in charge, "I determine which goat is the best sacrifice because I have the best hat."

Now add in all the problems that exist in organized religion today, greed, fear, power, control, believers, and liars. At this point trying to explain modern day Christianity would be like unraveling Xmas lights with bowling balls for hands. You'd need first hand knowledge of the inner circle in charge along with the most powerful individuals dating back thousands of years.

Religion is simply the natural evolution of a sentient species. If we meet an advanced alien race one day I'll bet the farm that they can tell us about the religious phase of their history. Religion is basically the terrible two's when the favorite word is "why?" A lot of people want to feel that humanity is special as if religion is something only we could come up with. We're not special, we're just the only sentient species we know of.

Religion was invented when the first con man met the first fool. This is often attributed to Mark Twain, but he probably didn't say it. Sounds about right to me.

I suspect that in part, it performs the function of delivering some illusion of control of an unknown after life. They are dependent upon that belief for piece of mind...otherwise why would they get so upset when their belief is challenged by a non-believer.

I think it’s just something that’s always been around, and people just keep reaching it to their kids, and they never teach them to think for themselves, but I look forward to a time when it will no longer exist…

Christianity became popular as the world went to s*** do to a comet passing and put loads of dust into the air. Causing climate change rapidly. Up until that time they had been Pega Dennis Druids and they figured out that this was not working so Christianity was on the rise at that time and everybody switch to Christianity. Unfortunately this was followed by the Black Plague and mass starvation in Europe. So that didn't work out too well either but by that time there were so many monasteries and churches that they stuck with it. I truly hate speech to text. It was Druids paganism and the like.

People are afraid to die. No afterlife is unacceptable for many. Why accept reality on realties terms when you can believe in warm fuzzies. It also may appeal to peoples narcissism. Look at me, I'm special.

Mystery. Without mystery there is no religion. There is the mystery of death. There is the mystery of life, and the purpose of life. There is the mystery of the Good, and there is the mystery of Evil. Knowledge is the enemy of mystery. In Genesis, Adam and Eve in the Garden of Eden were FORBIDDEN to eat the fruit of the Tree of Knowledge of Good and Evil. And once they partook of this knowledge, which destroyed mystery, they were cast out of paradise for their sin of knowing too much.

Belonging to a formed group is a part of herding behavior. People join groups for shared beliefs shared professional interactions and more. But people often join groups for protection and safety from real or imagined threats from the world. Think of cults (which Christianity started out as being), gangs, organized crime, and religion. People seek safety and comfort through these groups and will defend it to the death at times (Crusades, criminal behavior, the KKK etc)... It is my view that people with no advanced sense of self outside of the group stay in the group for what it offers them. If no desire occurs to individualize him or herself, they will remain content to stay "in their comfort zone" and demonize all others who become what they secretly wished they had the courage to be...their own person. that is my view of it all

If you go back far enough in history, thousands of years ago, long before we had technology to explain a lot of things in nature that are easily explainable now, these things were attributed to a god or gods.

It's to cope with the brutality of life. It's a coping device

Fear.
To assuage fear.

it simply serves to answer the socialization needs of the adults who shared stories of the answers they made up to satisfy the kids curiosity and to help domestication.