Board Thread:Warhammer 40k General Discussion/@comment-2253300-20130211000751/@comment-7232811-20130409174514

In the Imperial Infantryman's Handbook (or whichever one it is) it also mentions the 'ruinous powers', & gives a brief description of what they can do to people, but does not mention about things like daemons, CSM, or the true nature of the warp (of what the Imperium knows about it). So from that, even low level people in the Imperium would have a knowledge about the ruinous powers, but not know anything much about it, other than it is to be avoided like the plague & to be purged like a rat infestation.