When John wrote his first epistle, a heretical teaching was circulating, that of docetism – Jesus was not really a man. So serious was this problem that John thought it part of an antichrist scheme (cf. 1 Jn. 4:2-3). John believed this denial was a serious problem for Christianity. We will now peruse the NT to learn why Jesus had to be fully a human man if he was going to be the Messiah and earn our salvation.
Jesus was our representative. As such, he obeyed for us where Adam & Eve failed and disobeyed. There are parallels (cp. Rom. 5:18-19) between Jesus’ temptations (Luke 4:1-13) and what happened in Eden (Gen. 2:15-3:7).
If Jesus hadn’t been a man, he could not have died in our place and paid the penalty that was due us (Heb. 2:14-17). Jesus was a man, not an angel, not a spirit because God was interested in saving people, not angels or spirits. Regarding atonement, it is important to recognize that unless Christ was full human, he could not have been a substitute sacrifice for us.
Because we are alienated from God through our sin, we needed a mediator between ourselves and God to bring us back to him. This mediator needed to both represent us to God and represent God to us (1 Tim. 2:5). In order to fulfill this role, Jesus had to be fully human and fully divine.
First Pres Joliet 
May 21, 2024 at 5:06 am
C.R. This is also that doctrine, expressed in the Feast of Tabernacles, of God dwelling amongst men. In remembrance of Israels days in the exodus, where God took up residence in the Holy of Holies, and tabernacled with men. Jesus also fulfilled that in His dwelling on earth amongst men, a suffering servant, able to identify with the poorest, and the wealthy, most powerful of them.
Good writing.
Karl
May 21, 2024 at 9:59 am
Karl, in many ways this “fully man and fully God”quandary is like the Trinity. Its necessity is straightforward and needed. Its how? is beyond our reach. Without such cases, faith would not be necessary. Craig