User blog comment:Raffney/Timetravel in 40k OR is the Emperor a Chaos God?/@comment-8881468-20180224204647/@comment-8881468-20180225184835

Lorgar was shwn a vision of thins that might come to pass, not more not less, chaos wished to influence him.

The chaos gods are emotions made manifest. None of them was a creature in the materium that then got power in the immaterium. They are merely the "personified" amalgamation of an emotion. Slanesh is merely the concentrated essence of sensation in all it's facets, pleasure or pain, hate and love, tipped over the edge into creation by murderfucking of eldar. There was never a consciousness in the materium, from which slanesh evolved, all that happened without control in the immaterium.

The creation of the chaos gods themselves as avatars of their respective aspects/facets makes them immortal and indestructible, unless you kill of all life that creates the warp.