A long time ago there was a village by a river which, every year, would flood the surrounding plain and ruin the village and its buildings - but it left behind rich soil that allowed for bountiful harvests.
One day, one of the villagers went to the marketplace and proclaimed to them, "Fellow villagers! I know when the floods come, for my god Sirius tells me!" Of course, he was laughed at.
Months later, that same villager appeared again in the marketplace shouting "The god Sirius has told me that the floods are coming! Gather your stuff and head to the hills!" He was laughed at, but a few saw that they had nothing to lose, so they followed. Sure enough, two days later the river swelled and flooded the village. From then on, whenever the man said that Sirius told him that the floods were coming, they packed their belongings up and moved to the hills.
He had become the first priest.
Years later, he said to his son, "Now that you are almost a man I will let you meet our god, Sirius." In the evening, he led his son up the hills and pointed to a star. "You see that star? That's Sirius. When that star is on the horizon, the floods come."
And so Religion was born.
This story was related to me by my 10th grade history teacher.