“ Thunder and lightning is the sign of their shamans hunting and killing demons. Children's souls must be protected for their souls are not firmly in place yet and are easy for demons to take hold of. The shamans must hunt and destroy them and each break of thunder is another death of a demon hunting for souls.”
“ When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.”
“ On some of the islands off the coast, the rites of the local fertility god revolve around ceremonial death and rebirth. The religion's priests have overcome this cycle, however: Each of them is actually undead, ceremonially slain and 'reborn'! Their religion is otherwise unremarkable, being an odd offshoot of the mainland's religions. The priests vow to resist their undead cravings, seeing these as the 'cycle of life' attempting to reclaim their spirits.”