Let's say that there is a completely isolated human world out in the 40k galaxy. Its never come into contact with the Imperium at all. The last time it had any contact from beings beyond their own planet is all the way back in the Dark Age of Technology. If a cult dedicated to the Powers of Chaos cropped up on that planet, would the people of that planet refer to the Gods by the names that we know them by or would they have their own identities unique to the history and culture of this one planet? Its always been implied that the Gods of Chaos had many names given to them by many different peoples and cultures over the ages so I would guess that on this hypothetical world would give them their own names. This got me thinking. Where did the names Tzeentch, Khorne, Nurgle and Slaanesh come from exactly?
My guess would be Lorgar. He was the one that truly instigated the Horus Heresy after all. It is said in The First Heretic that Kor Phaeron preserved a small portion of the pre-Imperial culture on all worlds that the Word Bearers brought to compliance. Lorgar had to reconquer every world he had brought into the fold of the Imperium and that would have given him ample time to study all of these worlds' understanding of the nature of the Gods. It is my personal belief that Lorgar hodgepodge'd the cultures of many different worlds together to come up with his own philosophy and understanding on the nature of the Warp and Chaos which he recorded in the Book of the Epistles of Lorgar. That book spread out among the Traitor Legions in the Lodges which gave form to their own corruptions and eventually those Legions embraced Chaos in their own unique ways which were used by Lorgar as fodder to further expand his knowledge of Chaos. The Lorgan Epistles became the "Orthodoxy" for worship of the Gods and were spread throughout the galaxy where they formed the root of Chaos Cults for the next 10,000 years. All conjecture of course but its a theory that makes sense to me at least.
Is there any more official sources detailing how the discovery of Chaos worked?