To be 100% something means that one is comprised all it's constituent parts. So if one is 100% god then there is no part of god that your are not. If god is made up of parts ,1,2,3,4,5,6, and 7, then you would comprise parts 1,2,3,4,5,6, and 7. You couldn't be god and only comprise parts 1,2,3,5,6 and 7. So when you say that " they (the father, son, and holy ghost) are separate persons. But they are all still fully god. this implies that if the son, for instances, is fully god then he is also the father, and the holy ghost. because they are essential parts of god. For the son to be god but missing parts father and holy ghost implies that he is something less than a full god. He would not be fully god.