The only one he allowed knowledge to was Magnus because it was a necessity *psychic powers*. He wanted there to be no knowledge of the Chaos Gods, because then how can you worship what NOBODY but one person knows even exists?
The theory was that if he could unite the Galaxy under a secular banner (or debatable worship of himself) that the Chaos Gods would cease to be a threat because they would have no power.
Actually, he was termed " The New Man" and was basically, as you put it a lot of early psykers. The way it is written, and termed, is that in ancient times, a lot of shamans (pyskers) foresaw the ruinous power of chaos, and commited mass suicide to combine their spirits into one, strong being, " The New Man". From what I can tell, he walked the earth in carious guises, possibly being mystical people of power through the ages. What he tried to do, was to stop Chaos in its tracks, albeit in a losing battle. Chaos gods were formed, in part by the gestalt pyschic mass of sentient races. The immaterium, also known as the Warp, was actually pretty serene and harmless, back in the times of the ancient ones. The problem was, the necrons, and the c'tan. The necrons wanted to become more, as they were a perpetually dying race, so they made a deal with the c'tan, and become the necrons we know today. They waged war against the old ones, as they were jealous of their technology and immortality. they had actually waged war on the old ones before becoming the soulless necrons, but failed miserably. Eventually, with the c'tan as allies, they managed to push back the old ones to their last remaining fortresses, and in desperation, the old ones created the eldar, precursors to the orks and another race that escapes me. At that time, due to the eldar being created solely for psychic combat, the immaterium changed from serene rolling waves of energy, to crashing, violent waves they desribe today. the beings inside were warped and changed to reflect the upheavel in the psychic conciousness of senties species. That, is how the chaos gods were born. From the emotions, ranging from fear through anger. Afaik, Slaneesh was the last god that was born, due to the hedonistic ways of the eldar. Khorne, Nurgle and tzeentch were around way before Slaneesh. There is also a 5th god, Malice/Malal, although his back story isnt as rich or detailed.
The Emporer in the story line of 40k created many of Earth's major religions, he then watched them get used by evil men and become perversions of what he had tried to create. The Emporer also never felt the need for Faith, he always either knew the answer or found/created one with Science/Physic power. So the concept of Faith is one he never fully understood except as a method of weakness and evil as he observed over the centuries. He didnt abolish worship persay, he similpy meant people to put faith into Science and Reason as opposed to Relgion, thinking that this would weaken/kill/ dissolve the Chaos gods and bring the Warp back to the calm state it was in during the Old Ones time. He knew about the Hours Hersey when the Chaos Gods stole the Primarchs. Indeed he even had a chance to stop it from happening but didnt. (reference the Hours Hersey series) At the very least he knew it had the potential to happen. I agree that it would have went better had he chosen from the begining to say he was a God, but thats not where his mindset or goal for mankind was. He had tried the relgion thing, it failed. Chaos uses worship, he doesnt like that. He wants to usher in an age of technology, reason and science, claiming to be a god undermines that. I personally think he had an idea of future events past the current timeline of 40k, could very well be the Star Child theory or that he would reincarnate as the Shamans did before they merged to create him
The Horus Heresy and the relation between The Emperor and Horus seems like an inspired story of God and Angel Lucifer who was cast out of heaven.
Personally I think the Emperor had doubts of what his sons would become all along ever since their abduction by the Chaos Gods. So he knew that he would not shape the foundations of their characters. They would be their own men. Knowing Horus was his proudest son, he was confident in leaving him to lead the great crusade. But I don't think the Emperor truly appreciated how much his sons needed his presence and leadership or understood how they viewed him, e.g. Lorgar. He left them high and dry with no explanation of what he was doing back on Terra. Basically I think in his pursuit to advance humanity in the galaxy, he neglected his children and simply let them fall. Anyways, regarding the Fate of the Emperor....I don't believe in the Star Child theory. IMO after being killed, his spirit(s) has been dispersed into the immaterium to wander for 10 thousand years. I think a plot where individuals who belonged to the lineage of Shamans who formed the Emperor in the first place will be found throughout the Imperium. They will each embark on a quest to find their 'shard of the Emperor', resulting in them eventually meeting upon Terra and recasting the ritual that brought the Emperor to life. My 2c.
Threads like this always annoy me because we will never truly know the answer. We could argue about this forever and ever but GW is never gonna tell us because then they wouldn't have a franchise anymore. Even if they did it would probably be so vague and unsatisfying we would hate it regardless. Anyway the whole point is the struggle between the two, good and evil, look at 'Mechanicum' the Dragon of Mars. It's all about the struggle. Also if we're asking whether he knew or not, he did. End of story. He created the Mechanicum He set that plan in motion tens of thousands of years before. He is an anathema to the powers of the warp, look at the Grey Knights. They're just a tiny little bit of his power. It is reasonable to assume that the Emperor is greater than the sum of all the grey knights put together. One of them is romping around the warp eternally killing things. The Emperor was not a fool, he knew that the Primarchs were fallible. He killed two of them for not being strong enough. The way of beating chaos would have been to let Horus win, Horus burns out humanity in a few hundred years and the chaos gods die because Horus goes insane and murders the galaxy. That's why the Alpha Legion sided with Horus. The Emperor couldn't let that happen because humanity would be destroyed. Or alternatively he is waiting for another psyker of his caliber to come along. Human psykers are getting more common and more powerful, right? So he's just waiting for psykers who can match or exceed him to lead humanity into a new age of light. Until then it's just gonna get worse and worse. Star child theory? Lets not forget the Terminus Decree. Anyway that's the joy of 40k right? It doesn't actually matter.
Reference HH series? Which book? I have read all of them and the closest that Emps has ever gotten to even semi-semi-semi-insinuating that is in The Outcast Dead, when he tells Kai that you can be either all-powerful or all-knowing, but not both. That says that he's somewhere in between and doesn't know everything, which would mean he didn't know about the Heresy or how it would play out.
I still think Horus fell way too easy to chaos...maybe I just haven't read enough books yet, maybe they explain more later but from what I remember(spoiler below): Has the vision/dream w/e...figures out it was Erebus showing him sht all along, then sees magnus, says he can't trust them nor can he trust what Erebus showed him, wakes up, X months pass, Erebus still at his side plans the Heresy... Did I miss something? Some detail that explains it all? I think the Emperor knew something was up the moment he called Dorn to come fortify the palace...maybe not everything, but still...
