I was just thinking about the Emperor-worshipping humans in the Tau Empire. It occured to me I don't think GW have really told us anything significantabout the principles of the imperial cult, it seems to be tied in to the Imperium itself. Given that the Emperor didn't think himself a god in the first place, it confuses it even more.
How can a religion of such size and devotion have no core commandments, and more to the point how does the Ecclesiarchy get around it?