All three works have emphasized the transitory nature of the material world and the transcendence of the realm of rational thought, belief in god, or living in the ways of Krishna. Plato and the Gita especially emphasize the necessity of people doing what suits them best. Meanwhile the concept of an omnipotent, omnipresent, omniscient god from which all existence must come from directly parallels Krishna and all of existence, mentality, sensation and thought existing within him.
So we cannot sin except of our own fault, yet we cannot be righteous without the intervention of god. This seems to be a far too convenient of a policy to be another "we can't understand god" ambiguity. Why can god take no blame in sin (because of free will) while he takes all credit for virtue (because of grace)?