Last night I was reading about Lorgar, the Primarch of the Word Bearers. I had no idea that the Imperial Cult is actually heretical to the Emperor’s own Imperial Truth. I didn’t realize that the Space Marines do not acknowledge the divinity of the Emperor. I did know that the Adeptus Mechanicus didn’t. It was interesting to see that inadvertently, the Emperor punishing Lorgar for worshiping him basically led to the Horus Heresy. Basically, the whole Ordo Hereticus is basically dedicated to the ideas that got Lorgar in trouble, that started the Horus Heresy, and earned the Emperor his permanent place in the Golden Throne.
Oh sweet, sweet irony.