[@Lucidnonsense],
Dragon cultists are know for their sacrifices to dragons or gods for fortune or various things, thus has given them a bad name with many villages and revered as horrible or satanic. Hence when Crim (a dragon priestess) went to one of the villages in the beginning she was called a witch and set to burn. Many are revered as sorcerers or witches by most people. Some hold them in high standings due to their ability to tame dragons. 

Mages and Cultist have a bit of a feud due to the misconception that mages and cultists are the same. Mages are also considered sorcerers or witches. However, they can use different kinds of magic. Cultists lean more towards dark magic and forms of necromancy, while mages are more elemental or earthy. For instance, Crim can heal as a form of "necromancy". And the mage we have right now is a fire mage, mostly dealing in fire aspects. Mages stand more for earthly powers while cultists stand more toward heavenly or hellish powers and can be often mistook for a demon.

Hopefully that gives you an idea of the two. If not, I'm sure either of my co-gms would be happy to help you understand it in a different way. :)