It's a little known fluff fact that the Inqusition, the Ecclesiarchy, the Astartes, and, indeed, The Emperor himself are really just figureheads and puppets manipulated by the Grox Burger Cartel. The biggest conspiracy in the 40K universe is that all the current problems facing the Imperium, be it chaos, tyranids, or the necron are fascimile threats created by Groxxers'ma'Boxxers (tm) in order to drive humanity to seek comfort foods, thereby increasing revenue.
Of course, Groxxers'ma'Boxxers fiercely guards this secret. You think exterminateus is meant to wipe out traitorous planets? Ha. Whole worlds have been known to disappear and people are cut off mid sente-