As a parent I have a strong desire to raise my children with the same values that I have. For people who practice organized religion, you can’t really have the “values” part without the religion part. It all fits together into a cohesive whole. Young children also have a strong desire to mimic their parents, while at the same time wanting to know “why?”. How does one explain to kids why you’re celebrating a religious holiday or headed off to church/synagogue/etc... without teaching them about God? Most organized religions also have imperatives for passing on the knowledge to children. It’s totally incompatible with a person’s own belief system to not raise their children in their faith.
Many people for thousands of years have devoted their lives to the search for Truth. It is a journey that takes a lifetime. I don’t believe there is some moment in time where one is able to discern fact from fiction when it comes to the big questions of the meaning of life.