It is impossible for any part of God, even if incarnate, to decompose in any way and still be considered God. The everlasting, one God, in whole or in part, does not die, disintegrate, or decompose: ‘For I the Lord do not change.’ (Malachi 3:6). Did Paul invent God-Son concept to attract Romans?
You state that it is “impossible for any part of God, even if incarnate, to decompose in any way and still be considered God.” My response to this is to ask this question: Who says so? Who has the right or authority to say that this is impossible? According to what biblical principle or what other principle can a human simply declare that God–the Creator of the universe–cannot have to power to incarnate himself in mortal human form? Please provide for me proof of this reasoning and proof that the actual God who exists–a God who makes mortal flesh–cannot occupy mortal flesh. It seems that in this case you are simply making a claim but providing no proof or even evidence to support this claim. Perhaps what you should say is this: It is my belief that it is impossible for any part of God, even if incarnate, to decompose…. I could accept such a statement of belief, as it is your privilege to believe what you will. However the biblical statements about Jesus–who is God–seem to contradict this conclusion, at least as I see it.
The fact that God changed his mind when asked by Abraham to relent from destroying Sodom does not mean that God himself changes. When I “change” my mind, it does not mean that I have changed myself in any fundamental way. This is even more true of God. Like it says in Revelation 13:8, Jesus is a lamb who was slain from the foundation of the world. In other words, from God’s perspective, Jesus was incarnate and killed for our sins from before he created the world. God did not change when he came in the form of a mortal human. God has always been a relational and sacrificial God. Malachi 3:6 is not a proper proof text that God cannot take on human form. If God decided before the creation of the world to come as a mortal sacrificial lamb, then he did not change when he in fact did so. Besides, apparently he did, as Jesus of Nazareth performed many mighty deeds, he was raised from the dead, and he, himself claimed to be God (John 8:57-59). The facts of the matter disprove any resort to reasoning. Jesus is God, and he proved it by being raised from the dead. Jesus called himself Son of God, so that settles it the best that I can tell.
No, Paul did not invent the God-Son concept to attract the Romans. In fact, Paul generally did not even appeal to Romans. He mostly appealed to Greeks, not Romans. Besides, it was Jesus who claimed to be the Son of God originally, not Paul. Jesus called God Father many times and he called himself Son many times as well. Paul could not possibly have invented this theological idea. In fact, it is not Paul who is the principal author in the New Testament who discusses Jesus as the Son of God. It is John who is the principal author describing Jesus as God-Son, not Paul, so how could Paul have been the inventor of this idea? No. Definitely not. It was not Paul who invented the idea of Jesus as both Son and God.