Yes, I believe that Christ could have sinned and if He had He would no longer have been righteous and therefore could not have remained in the Godhead. That was the incredible risk that God took for us. But since Jesus is God, (although with His own personality) God could trust Himself to pass the test, which Jesus did.
God is wonderful.
More like..."the Gods are wonderful". Here you are affirming once again a belief in three different gods, not a single God. If God is one (Deuteronomy 6:4), then God cannot sin against himself and separate himself from himself. For that to happen you would need three separate gods, not one God in three persons. Lord Jesus explicitly affirms his union and equality with the Father in the Scriptures:
John 10:30
"I and the Father are one".
John 14:10-11
"Do you not believe, that I am in the Father, and the Father in me? The words that I speak to you, I speak not of myself. But the Father who abideth in me, he doth the works. Believe you not that I am in the Father, and the Father in me?"
John 5:19
"Amen, amen, I say unto you, the Son cannot do any thing of himself, but what he seeth the Father doing: for what things soever he doth, these the Son also doth in like manner."
This union is not merely a voluntary act from the Son, something that he chooses to do but as the last verse states since he cannot do anything of himself, it is something that he does of necessity. Since God cannot deny himself (2 Timothy 2:13), then naturally, the Son being God and one with the Father, who is himself perfect (Matthew 5:48), cannot sin or do something against his will, since he too is perfect. Note also on the second set of verses that just as the Son cannot do anything by himself, the Father who abides in him is who both speaks and works everything in him. The reverse as he affirms is true, he is in the Father as the Father is in him. What this means is that each person of the Trinity is within each other. There is no separation between the persons but each one is within the other, there is no such thing as the Father willing some thing and the Son or the Spirit another thing and much less of the Son willing anything against the Father. In fact, not even the possibility of it can be admitted for that would destroy the unity of the persons and when it comes to sin, it would entail a lack of virtue in God, for the possibility of sinning far from being a "freedom" is itself a defect.
Yet, as you have affirmed, the Son as well as the Father could sin, so, if the Son had sinned during his ministry he would not only have become a fallen member of the Godhead, but since whatever the Son does the Father does as well, it would mean that the Father would have ALSO sinned with the Son, leading, as you believe, to a destruction of the Godhead! Hopefully the reason why the Son not simply did not sin but cannot sin is clear now.
The unity between the persons is also manifested when God is about to create man (Genesis 1:26) and we see it again in the gospel of John, where we read that
"All things were made by him: and without him was made nothing that was made. (John 1:1-3). St. Paul also affirms the intimate and inseparable union between the Father and the Son:
Colossians 1:15-17
"Who is the image of the invisible God, the firstborn of every creature. For in him were all things created in heaven and on earth, visible and invisible, whether thrones, or dominations, or principalities, or powers: all things were created by him and in him. And he is before all, and by him all things consist."
Hebrews 1:2-3
"In these days hath spoken to us by his Son, whom he hath appointed heir of all things, by whom also he made the world. Who being the brightness of his glory, and the figure of his substance, and upholding all things by the word of his power..."
Note here that not only the creation of all things but also their continued existence are things that are said to be the work of the Trinity. This is the same that we read in John cited above. The unity of the Godhead is maintained and as Lord Jesus himself states, as he abides in the Father and the Father in him, there is an unity of operation in all that God does where the three persons of the Trinity always work together. To separate the persons of the Godhead is to destroy the Godhead. To say that the Son could be separated is to affirm an independent existence of the Son by which he is his own essence independently of the Father and the Spirit. It is to affirm two or even three separate gods. By doing that you step away from monotheism and land into tritheism. It is to affirm not one God, as the Scripture does but three. The denial that Lord Jesus is both fully human and fully God, one person in two natures naturally leads to a separation of the Godhead and to the necessary affirmation that the Son can be a separate God independently of the Father and the Spirit, something that is, of course, contrary to Scripture.
Now, what about some of the verses that seem to imply a separation of the Father and the Son? There are a couple of them, it is true, but such verses far from affirming a separation of the Trinity, simply affirm the two natures of Christ. For the sake of brevity, I will focus on a single one in this post that is commonly used.
Matthew 27:46
"And about the ninth hour Jesus cried with a loud voice, saying: Eli, Eli, lamma sabacthani? that is, My God, my God, why hast thou forsaken me?"
Keeping in mind the unity between the Father and the Son shown above, the first thing to note about this verse is that Lord Jesus
does not says God the Father, it just says God, Lord Jesus is very careful about the words he uses. This is a very important distinction. This cry is said to fulfill a Messianic prophecy, it is the same saying found in the Psalm:
"O God my God, look upon me: why hast thou forsaken me?" (Psalm 21:1). This chapter is heavy on the fulfillment of several prophesies, this is the context on which things are happening here. The Psalm 21 closely matches many of the events that take place in the life of Christ, which we see in Matthew 27:
Psalm 21:1
"O God my God, look upon me: why hast thou forsaken me?"
Matthew 27:46
"My God, my God, why hast thou forsaken me?"
Psalm 21:8
"He hoped in the Lord, let him deliver him: let him save him, seeing he delighteth in him."
Matthew 27:43
"He trusted in God; let him now deliver him if he will have him; for he said: I am the Son of God."
Psalm 21:17
"The council of the malignant hath besieged me. They have dug my hands and feet."
A clear parallel with his crucifixion and the trial before the council.
Psalm 21:19
"They parted my garments amongst them; and upon my vesture they cast lots."
Matthew 27:35
"They divided my garments among them; and upon my vesture they cast lots."
Read the entire Psalm, it is quite nice. With the cry in Matthew 27:46, Lord Jesus was alluding to the whole Psalm and given it's triumphant ending, far from being a cry of despair or of separation, it is one that carries the hope of vindication. Specially of relevance is the verse which says:
"Let all the seed of Israel fear him: because he hath not slighted nor despised the supplication of the poor man. Neither hath he turned away his face from me: and when I cried to him he heard me." (Psalm 21:25).
It is also important to note other things that occur right at that moment. For example, it was right at the ninth hour that the cry was made (Matthew 27:46), why? Because the ninth hour is the exact time of the Jewish afternoon prayers (Acts 3:1, Acts 10:30). Christ was also a faithful Jew after all so it is only logical that he would say his prayers at the appointed hours (obedient unto death and all that...). This is his last prayer.
Note also the three hours of darkness that go right before that (Matthew 27:45), his claim that:
"It is consummated." (John 19:30), right after they gave him the vinegar to drink, the events that occur right after he gave up his spirit (Matthew 27:51-53) and the comment of the guard who realized right away who Christ was (Matthew 27:54). All these events point clearly to an eschatological sign, much more than a simple prayer and certainly not a feeling of being separated from the Father. Far from a cry of separation, instead this is his declaration that he is the fulfillment of that Psalm, which was seen by the Jews, many of whom were present there, as a messianic Psalm of which Christ is the fulfillment.
Evo