They believed that when a person died, everyone's soul went into the Lower World. There, they were conducted to the "Hall of Truth", and judged in the presence of the "god of dead", and 42 "judges of the dead". Their deeds were placed in a vase onto one end of a special scale. On the other end of the scale, was placed an "emblem of truth".
If good deeds outweighed, they were led into the "pool of peace". If there were not enough good deeds, the soul was sentenced to a series of trans-migrations into the bodies of more or less clean animals. The type of animals they had to migrate to and the length and number of migrations, depended on how short they were of attaining the level of righteousness.
If after many tries, the soul still did not become good enough, it was annihilated by the "god of light".
If a soul did improve, it was sent through the basin of purgatorial fire, guarded by four ape-faced creatures. Than, the soul was to accompany a good god Osiris for a period of 3000 years. And than, the soul returned to its former human body, and again relived its life as a human on earth.
The process was repeated until a mystic number of years had gone by. And than, finally, was absorbed into the essence of god, to become one with the Divine Essence from which the soul emanated in the beginning. Thus, the true and full perfection of their being was attained.
As I was writing this article, a few bells went off.
First of, there's a strong resemblance with an ancient biblical idea that the soul was not dead after a human body died. Ancient Hebrews had an understanding that the good souls entered into a "pool of peace" too. That is another indication that both religions had a common ancestry, the original belief of the human race in the One God.
But that's about all that is common between the Hebrew understanding of the after-life and the Egyptian understanding.
Re-incarnations? Buddhism is even older than we thought.
The purgatory fire? I love all Christian denominations. But this concept is found in the ancient Egyptian religion, not in the Bible.
Also, the idea that human souls existed before they were born on earth, also comes from the ancient Egyptian religion, and found nowhere in the Bible.
Lastly, it's a more convenient story to the end of all living things than the reality. Millions of ancient people lived and died with the idea that you can't really eternally mess up, you'd be given a lot of chances, and if all fails, you'd just be annihilated. Hopefully many of them believed Jesus, and got out, when He descended into the Lower World after dying for the sins of the human race.
Sources:
Ancient Egypt By George Rawlinson, M.A., print, London 1886
Image source: By Muntuwandi at en.wikipedia [Public domain], from Wikimedia Commons