Behold, my servant....His visage was so marred more than any man, and his form more than the sons of men (Isa. 52:13-14). According to the description here, in order to be God’s servant, the Lord needed to be a man. His visage was so marred, more than any man, and His form more than the sons of men-this shows He is a man.
The entire chapter of Isaiah 53 prophesies concerning Christ. For he shall grow before him as a tender plant, and as a root out of a dry ground: he hath no form nor comeliness; and when we shall see him, there is no beauty that we should desire him. He is despised and rejected of men; a man of sorrows, and acquainted with grief: and we hid as it were our faces from him; he was despised, and we esteemed him not.... He was cut off out of the land of the living....And he made his grave with the wicked, and with the rich in his death....He was numbered with the transgressors (Isa. 53:2-3, 8-9, 12). These few verses fully depict the conditions and experiences of a man. Hence, Christ has to be a man, and He indeed became a man.
Behold, the days come, saith the Lord, that I will raise unto David a righteous Branch [or, Shoot or Bud]...and this is his name whereby he shall be called, The Lord Our Righteousness (Jer. 23:5-6). This word refers to Christ. He is David’s Shoot, that is, David’s descendant (Matt. 1:1; Rev. 22:16). He is The Lord Our Righteousness; He is also David’s Shoot. He is God; He is also man. Isaiah 4:2 says that He is the branch [or, shoot or sprout] of the Lord-He comes out of God and has God’s nature. Here it says He is the Shoot of David-He comes out of man and has a human nature.
The prophet Daniel declared, I saw in the night visions, and, behold, one like the Son of man came with the clouds of heaven, and came to the Ancient of days, and they brought him near before him. And there was given him dominion, and glory, and a kingdom, that all people, nations, and languages, should serve him (Dan. 7:13-14). In the visions Daniel saw Christ receiving the kingdom from God and coming back to earth to rule (cf. Luke 19:15: when he was returned, having received the kingdom). Christ in this vision appeared as a son of man. This means when He shall have received the kingdom and come back again to this earth to rule as a king, He is a man (Matt. 26:64). It is with the status of a man that He receives the kingdom from God and comes back to rule over the nations of the earth.
But thou, Bethlehem Ephratah, though thou be little among the thousands of Judah, yet out of thee shall he come forth unto me that is to be ruler in Israel (Micah 5:2). This prophecy says that Christ was to be born in Bethlehem (John 7:42) and become a man to rule for God. This also proves that Christ needs to be a man.
Additional Old Testament prophecies concerning Christ are: I will bring forth my servant the Branch [or, Shoot or Sprout] (Zech. 3:8); and Behold the man whose name is The Branch [or, Shoot or Sprout]; and he shall grow up [or, shoot] out of his place, and he shall build the temple of the Lord: Even he shall build the temple of the Lord; and he shall bear the glory, and shall sit and rule upon his throne; and he shall be a priest upon his throne (Zech. 6:12-13). All these designations refer to Christ. He is God’s servant, He is a man, He is called the Shoot. He will build the temple of the Lord; He will sit on the throne and rule and be a priest. He can do all these things because He is a man. It is with the status of a man that He will come and do all these things. These are strong proofs that Christ needs to be a man, a real man, a complete man.
Furthermore, Zechariah 13:7 says, Awake, O sword, against my shepherd, and against the man that is my fellow, saith the Lord of hosts: smite the shepherd, and the sheep shall be scattered. In Matthew 26:31 the Lord points out that this word refers to Him. He is God’s shepherd; He is the man that is God’s fellow. Although He is God’s fellow, He is still a man. This also proves that the Lord needed to be a man.