You know, for a group that yells "Heresy!" a lot, I couldn't recall the Imperium of Man- particularly the Ecclesiarchy- having a holy scripture upon which to base their religion on. Considering they have a heirarchical organized religion and all.
From the Horus Heresy, the Lectio Divinitatus that Lorgar wrote down started the organized religion around the cult of the Emperor. But its only mention is in the Horus Heresy and not much in later 40k Media. In addition you have these bigass books Ecclesiarchy and Inquisition Characters lug around.
>>3037487
>I couldn't recall the Imperium of Man- particularly the Ecclesiarchy- having a holy scripture upon which to base their religion on
Lectitio Divinitatus, mate
>>3037487
the lectitio divinitatus is the main script but basically every one of the imperial orders has a charter or codex that it treats as holy scripture. The codex astartes would be what space marine chaplains are hauling around