Heaven, a traditional theory of the afterlife generally tends to be set in the clouds. Lotsa people tend to go with the thought that their deceased relatives and ancestors are looking at you from heaven (the sky).
What IS a soul? That's another deeply debated question that has been pondered by people for generations. There are people that think that the soul, mind, and body are all separate things that are dependent on each other. If you're soul is taken, then your body will wither and die. If your brain is damaged, it can't tell the organs in the body how to do their jobs. and if your body dies, the soul has no place to be housed and your mind is sorta stuck there until it dies as well. I dunno.
"A sound soul dwells within a sound mind and sound body."
The Oka Compendium: A glorified record of my alt-a-holic-ism. May or may not be up to date at any given point.