Apollinaris saw that humans are tricky, fickle creatures, often irrational and unreliable, and he could not imagine God entering into that situation. His solution, then, was to imagine that in Jesus the problematic human spirit was swapped out in favor of the divine logos, giving us a Jesus who is less than fully human. Any Christology that tries to exempt Jesus from some aspect of being human is akin to the Apollinarian heresy.
