Final answer:
The primary reason that God cannot be a judge is that according to the premises provided, God is all-knowing, all-powerful, and all-good.
Step-by-step explanation:
The primary reason that God cannot be a judge is that according to the premises provided, God is all-knowing, all-powerful, and all-good. However, if God were to judge, he would have to choose between different options, and that would imply that there are alternatives to the best possible choice. Since God cannot fail to choose the best, this means that he is not free to make choices, and therefore cannot be a judge.