When confronted with a being, or power, calling itself the "Architect of Fate", I get worried for the main forces of the story. As a reader, we know that they're going to get sucked in to some twisted plot involving death, daemons, fire, and if they're really unlucky: Nurgle worshippers as well.
I can't help but think how things might have been different if the Emperor was upfront with his primarchs from the start. "Hey, Lorgar. When you're out and about in the big wide Universe, watch out for this belief called chaos. There's these warp aliens called Khorne, Nurgle, Tzeentch and Slaanesh. They like to be worshipped by realspace inhabitants. It's really bad stuff, son. They lie as well and call themselves by other names such as Blurrrghh. Stick with the Imperial Truth, okay? No? Okay -- its better to worship me than those others then".
The interested thing about the above thought train is that this is exactly the kind of conversation that happened in the alternate Universe Dornian Heresy where Lorgar's Word Bearers became the good guys of the piece. And look what good that did: Dorn got corrupted instead of Horus... hmmmmm.