The Gita itself presents a doctrine of Avatarhood which goes beyond the idea that a human being can through receptivity and development, open to the divine force and embody it, or that it can even take over and supersede the human individuality. The Gita directly states that the supreme Lord of Creation can and does on occasion, take direct birth through the process of Nature into the human form and acts from that platform from the knowledge, consciousness and power of the Supreme.
Sri Aurobindo explains the Gita’s statement in this regard: “The Divine descends by his own Prakriti into birth in its human form and type and brings into it the divine Consciousness and the divine Power, though consenting, though willing to act in the form, type, mould of humanity, and he governs its actions in the body as the indwelling and over-dwelling Soul…. From above he governs always, indeed, for so he governs all nature, the human included; from within also he governs all nature, always, but hidden; the difference here is that he is manifest, that the nature is conscious of the divine Presence as the Lord, the Inhabitant, and it is not by his secret will from above, ‘the will of the Father which is in heaven,’ but by his quite direct and apparent will that he moves the nature. And here there seems to be no room for the human intermediary; for it is by resort to his own nature…, and not the special nature of the Jiva that the Lord of all existence thus takes upon himself the human birth.”
Sri Aurobindo, Essays on the Gita, First Series, Chapter 16, The Process of Avatarhood, pp. 154-155