To avoid religious issues, there are no gods or anything.
The only powerful things are the Sun and the Moon. Well, and the 12 original souls.
Soon, the other souls formed, such as Bravery and Killer. At first, the soul of evil could be good, but they lost power over the centuries before life. Many evil souls helped create life and then created a large rock. A rock that only trapped the evil souls until it crashed. Even worse, the good souls became ball of fire where they had no control of what new souls were made of. After humans were centuries old, all the souls were released by a powerful sorcerer. The good souls gave him one wish. They did not realize that he was possessed by Greed. He wished for his soul, along with his friends', a scientist and a pirate, to go onto a beautiful secret place when they died. He also told them that he couldn't have saved them without his friends. They immediately promised each of his friends one wish. The scientist asked for infinite wishes, the pirate asked for them to be able to get new "crew members" each year.
They now come each Blue Moon, at sunset, and trap as many souls as they can.
Souls linger at Graves until midnight on a Full Moon. They then float to the Moon.
The Sun sends Souls back to Earth whenever a child is born.