I would not have any problem understanding and agreeing with that concept of 'Son of God' (figurative). Anyone close to God, would be a Son of God in that sense. However, if that is the case, why is Jesus(pbuh) (the Son of God' different from all the other 'Son of God'/Messengers mentioned in the bible ?
The reason why he is different is because he was the very first creation of God. He is the first angel God made. They existed together alone for perhaps eons of time before other angels were created. The book of proverbs describes his close relationship with Allah in Proverbs (written by King Solomon)
Proverbs 8:22
“Jehovah himself produced me as the beginning of his way, the earliest of his achievements of long ago. 23 From time indefinite I was installed, from the start, from times earlier than the earth. ...30 then I came to be beside him as a master worker, and I came to be the one he was specially fond of day by day, I being glad before him all the time,
This angel of God is called the 'firstborn' by the Apostle Paul, and all other angles were created 'through' him and its for that reason that he is the 'chief' or Archangel in heaven.
Colossians 1:15
He is the image of the invisible God, the firstborn of all creation; 16 because by means of him all [other] things were created in the heavens and upon the earth, the things visible and the things invisible,
Because of his high station, God has placed him as the head of the heavenly kingdom...and all the heavenly angels (including Gabriel) are led by Jesus in the service of the Creator.
You are contradicting yourself - read that again "those messengers were usually imperfect humans who eventually died" . I think at least according to your belief - Jesus(pbuh) died on the Cross, right ? Did Jesus explicitly state (clear and unambiguous) anywhere in the Bible that he would die to save mankind from sin ? I would expect that if that was his main mission in the world - he would at least do that.
unlike other humans, Jesus lived as a heavenly angel BEFORE he came to earth as a man. You know that Mary became pregnant by holy spirit (Gods power)... this means Jesus did not have a human father....he was more then human. His purpose was to be born in the flesh and die in our behalf. He was to pay the price of sin for every man woman and child. When he did that, he had accomplished his task, and thereafter he was restored to heaven as a powerful angel where he had originally been.
So he was nothing like any other prophet or messenger. He was Gods heavenly angel....the one through whom all things came into existence including us.
In your Quran, you know that God speaks in plural....
"We sent our messenger..." why? Allah is with his firstborn....its the same in the bible
Genesis 1:26
And God went on to say: “Let us make man in our image, according to our likeness
God speaks in the plural because he is not alone....his firstborn son is with him
"Divine justice required a perfect human life to save mankind" - did Jesus(pbuh) say that anywhere in the Bible ?
Yes. And not only Jesus, but also the prophets mentioned this too:
Matthew 20:17
Being now about to go up to Jerusalem, Jesus took the twelve disciples off privately and said to them on the road: 18 “Look! We are going up to Jerusalem, and the Son of man will be delivered up to the chief priests and scribes, and they will condemn him to death...and the third day he will be raised up.”
Matthew 20:28
Just as the Son of man came, not to be ministered to, but to minister and to give his soul a ransom in exchange for many.”
Isaiah 53:5
But he was being pierced for our transgression; he was being crushed for our errors. The chastisement meant for our peace was upon him, and because of his wounds there has been a healing for us...
11
Because of the trouble of his soul he will see, he will be satisfied. By means of his knowledge the righteous one, my servant, will bring a righteous standing to many people; and their errors he himself will bear
Isaiah 53:12
'... due to the fact that he poured out his soul to the very death, and it was with the transgressors that he was counted in; and he himself carried the very sin of many people, and for the transgressors he proceeded to interpose
What about the following statements in the Bible then ? So is God saying Justice means one thing for the mankind and another thing for Himself ?
[Ezekiel 18:20] “The soul who sins is the one who will die. The son will not share the guilt of the father, nor will the father share the guilt of the son.”
And:
[Deuteronomy 24:16] “The fathers shall not be put to death for the children, neither shall the children be put to death for the fathers: every man shall be put to death for his own sin.”
Ezekiel 18:20 does not apply to God or Jesus...it applies to sinful mankind. We are not punished with death because of Adams sin...we die because we commit our own sins.
The entire purpose of the Mosaic Law was to teach us this vital truth. If we sin, we will die.
If you look around the earth, you surely know that every single person born will die...why do they die? Because we are all breakers of Gods moral laws. When we break physical laws, we suffer or can die. For example, the law of gravity must be respected and obeyed or it can kill us. If we step off a high ledge we will come crashing to the ground because the law of gravity cannot be broken.
its the same with Gods universal moral laws. If we break them, we will die as Ezekiel 18:20 clearly states. "
the soul that is sinning, it itself will die"
And the mosaic laws were to show us the very immoral acts that bring forth death. Rebelliousness was death by stoning, disobedience to parents was death by stoning, Murder was death by stoning....etc etc etc. These moral standards, if we break them, will bring forth death.
the mosaic law was Gods way of showing mankind why we are dieing....it was only applicable to the Isrealites for a set time until the Messiah arrived, then it would be fulfilled because the Messiah would carry our sins so that we could be forgiven for sin and attain everlasting life through him. (this is side point but this is the reason why Christians do not adhere to the mosaic law)
God is not going to hold sin against us and demand the death penalty anymore....he wants mankind to live forever....he wants death to be done away with for good. Through submission to his moral laws and standards, and through faith in Jesus Christ, we can attain to such a future. Sin gives us death, but Jesus gives us life.
Since you brought up Adam(pbuh). According to your example of 'perfect human' Adam(pbuh) would be more of a perfect example since he was born of no father and no mother, whereas Jesus(pbuh) was born of a human mother.
Adam and Jesus are equivalents in that they were both created/born perfect. Being perfect meant they were without defects at their creation. In Adams case, he misused his freewill and chose to become disobedient to God...he did not submit himself to Gods will. But Jesus chose to fully summit himself to God...even in the face of death and bitter persecution he chose martyrdom because he was a true muslim. Adam was not a true muslim though...he was rebellious and under your law, would have been stoned for apostasy.