God is not Buddha and Buddha is not God. Why? God implies a being that is Almighty and that can controls other beings. the closest description of God that is being described by the monotheistic religions that can be found in Buddhism is either Brahma or the Maras, as it implies an almighty creator god that is in control of everything, and that has created everything in existence but not free from greed, hatred and delusion as he still needs people to worship him to grant clemency and to grant them happiness, and those who do not worship him or do as he says will be punished severely. That is what a God is, a worldly being that is more or less, conditional with his love and help, not that there is anything wrong with it, but it is definitely not what I would want to take refuge in as my happiness will depend on his benevolence and his moods. Why would I want to subject myself to something like that? To imply surrendering to a God is to imply that we put our own happiness and responsibilities in the hands of another being, and that being might not be free of the 3 poisons and can definitely harm us.
Dorje Shugden is not a god, or rather, no enlightened being is a god because they do not seek to control us, nor do they seek our prayers to gain favor with them. they only help and assist if we follow their instructions because doing so creates the causes and creates the opportunities that that allow them to help us. It is never about gaining favor from the Buddhas, or doing something to displease the Buddhas as they are free from greed, hatred and delusion. Since a god still has greed, hatred and delusion, and a Buddha does not, how can it be that a Buddha can be a god? sure, Dorje Shugden might have the attributes of a God or he appears to be one, but he is definitely a Buddha because he has all the qualities of one.