A view of reality not commonly espoused but one I hold to, spirits condemned, outside of our Lord hate each other, that is the nature of evil. They will work together in their hatred to destroy anything Godly. It is what they are left with and again in their nature as it is the spite they thrive on, the need to destroy anything good.
To that end the letter people work together because of that spite and hate of the demons influencing them but the demons left to their own designs infight and continue the hatred of each other.
Whoa! Sounds very accurate.