@Kid Cthulu
Well, unless you count the Salamanders, they're arguably TOO black~
@Anonymous
Of course they love the Inquisition; the entire Imperium is satirizing Christianity, with a god-like being who began the whole thing, who turned into a religious idol over the years (despite his whole manta being about Secularism and anti-religion, because he knew that worship of deities often leads to Chaos), the followers of which preach and practice the exact opposite of what he wanted. The Inquisition in 40k is essentially just the Spanish Inquisitors combined with Nazi Germany...IN SPACE!
As for the Rebellion, sort of. The Primarch Lorgar led the Word Bearers, who, as you can guess from the name, were all about spreading the "word". At first this was worship of the Emperor as a god, since, as Lorgar put it, his power and wisdom are so great, how can he be anything but divine? Big E disapproved of this, however, since, again, he wanted all Religion wiped out, especially any worship of HIM. So he told off the Word Bearers and destroyed their monument, which made them into angsty teens who went looking for a "New Truth" to worship, since their reasoning was there must be SOMETHING out there. Long story short, their search led them to the Eye of Terror, a rift between reality and the Warp, where they found the truth of Chaos. So, Lorgar wasn't a Fundy, he was just a person who HAD to have something to worship, even if what he finds are cruel, bloodthirsty dark gods.