Board Thread:Warhammer 40k General Discussion/@comment-24332685-20140111015135/@comment-6078851-20140119155533

bear in mind that any returning primarchs would most likely brand the imperium as heretical: they fought alongside the emperor as he attempted to remove religious worship from humanity. think how they would react to find out that the imperium is fanatically and irretrievably religious (isn't it against imperial law not to worship emps?).

i really think any returning primarchs, after a few had returned, would start a civil war against the lords of terra and specifically against the ecclesiarchy. it doesn't matter if the high lords brand them as heretics or even flat-out traitors because they personally knew emps, and the word of the high lords would hold no water against the word of the emperor, and by emps' own words, which the primarchs would remember, the entire governance of the imperium would be seen as heretical and traitorous.

and so the primarchs would see it as their duty to remove those traitors to the emperor...