Besides community, I think a second reason for organized religion is to keep the vision for a just and equitable society in front of people.
When Darwin’s Theory of Evolution was making big waves, the Christian church responded with the idea that the Bible was factually true. The same thing had happened centuries earlier with Copernicus’ new ideas about the universe. The church reacted as if it was the sole repository of all truth, spiritual and scientific.
What would have happened if the church had admitted that its teachings were about spirituality, not science? What would have happened if the church leaders had simply concentrated on their true mission? Instead of fighting science, it could have been an opportunity to give organized religion greater clarity and importance.
I can picture a response to Darwin’s supporters like this: Yes, evolution develops along the laws of natural selection and survival of the fittest. However, as humans we have developed the ability to envision something different. Our spirituality allows us to rise above the self-centered instinct for survival. Nature can be cold and cruel, but let us show you the more excellent way of love.
We are still human beings. We still need to rise above our basic evolutionary instincts for survival. Spirituality, I believe, is in part about that ability to envision and live into a society that is more than our natural evolution. It requires us to control our own moral evolution as individuals and society. That is a very god-like thing to do.