For at least as long as we have written records, people have had questions like: Where do we come from? Why are we here? What sets us apart from all other species? What do we all have in common? What causes natural disasters?
Just about every culture or people group has some kind of dominant religion. Opinions about exactly what religion is vary widely. There is even widespread disagreement within religions with the same label. Take Christianity for instance. There are major subdivisions such as Orthodox, Catholics and protestants; thousands of protestant denominations alone.
What is religion good for? Although it may change over time, religion explains the unknown like where we come from and why. Most religions have a creation story and sometimes also an end of time story or version of a perfect world. It provides some of the glue that connects us with one another, the cooperation we may depend on for survival. It provides a reason to live. It may provide a social structure or moral code.
Some say that, since religion is part of human nature, in a sense we all worship the same god except we do it in different ways depending on where we are and when. The details of religions may be different from place to place and change over time, but fundamentally the same for everyone.
Paradoxically, while religion may bring us together and give us a sense of belonging, religion has also caused some of the fiercest divisions among us.