Chizuk Emunah (Pt 2) Under the Microscope: Chapter 44

John 6:38, "For I [viz., Jesus], came down from heaven not to do mine own will, but the will of Him that sent me."

If Jesus alludes here to the descent of his soul to the earth, in order to inhabit the body, then he has pronounced a common-place doctrine, for every human body is possessed of a soul; but if he meant that he descended from heaven in flesh, then the assertion is at variance with the other accounts, according to which he was born of a woman in Bethlehem, in a manger. See Luke 2:7. Moreover, we see here an acknowledgment of the all-important fact of his non-identity with the Godhead, as he professed to be only the agent of Him who sent him. 

This is another objection that is hard to understand. John is referring to the idea of Jesus becoming incarnate, just as Paul states in Philippians 2.

Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant, being born in the likeness of men. And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross. Therefore God has highly exalted him and bestowed on him the name that is above every name, so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father. (Philippians 2:5-11 ) 

 Ancient Israel spoke about cosmology in terms of a layered system. At the bottom, was the depths of hell. Above it is the world where we live. Above that is the first heaven, also known as the sky or the atmosphere. Above that is the second heaven, or outer space. Above that is the throne of God.

This is what John means by descent. Jesus, who was in the form of God, did not consider his equality with the Father as something to be grasped, or to be held onto at all costs. Instead, he gave up this glorious position by taking on the form of a servant. He came down from the throne of heaven and became incarnate. While in this state Jesus was dependent on the Father in order to know what to do. The Father was in a better position in heaven than Jesus was on earth, given his self-limited knowledge.

This, like many of Troki's objections, requires that one not understand the models of the divine trinity or of the incarnation of Jesus. Once those are understood, many of Troki's objections evaporate.

In fact, Maimonedes gave support to the coherence of trinitarian monotheism when he responded to Hippocrates' claim that we have three souls.

Know that the human soul is one, but that it has many diversified activities. Some of these activities have, indeed, been called souls, which has given rise to the opinion that man has many souls, as was the belief of the physicians, with the result that the most distinguished of them states in the introduction of his book that there are three souls, the physical, the vital, and the psychical. These activities are called faculties and parts, so that the phrase “parts of the soul,” frequently employed by philosophers, is commonly used. By the word “parts”, however, they do not intend to imply that the soul is divided into parts as are bodies, but they merely enumerate the different activities of the soul as being parts of a whole, the union of which makes up the soul. (from Shmoneh Parkim)

 Maimonedes is arguing that the soul has different activities, and through those activities has a complex unity.