According to Spiritism,there are:
- Primitive worlds: The first incarnations of human souls happen in them.
- Worlds of tests and atonements: In them, evil prevails.
- Regenerating worlds: They are where the souls that still have to expiate acquire new strength, resting from fatigues of struggle.
- Blessed worlds: Where good overcomes evil.
- Celestial or divine worlds: Homes of the purified Spirits, where good reigns without mixture.
Planet Earth belongs to the category of worlds of tests and atonements,and that's why, on Earth, humans are exposed to so much miseries.
The incarnate Spirits (or souls) who live in a world are not forever connected to it, and don't go,on that world, through all the progress phases they must go through to attain moral perfection.
When those Spirits reach the necessary degree of spiritual evolution, they go live in a more evolved world, and so on, until they reach the condition of Pure Spirits.
The entire humanity is not living only in Planet Earth.