The New Testament teaches that Jesus was a man. For one thing, Jesus himself said so. For example, in John 8:40, Jesus said he was “a man who has told you the truth” [emphasis ours]. Jesus was not being disingenuous and hiding his “divine nature.” He was making a factual statement that reinforced what the Jews were expecting of the Messiah—that he would be a fully human man.
The apostles also taught that Jesus was a man. For example, in his sermon to the crowds gathered on the Day of Pentecost, the Apostle Peter made a very clear declaration that Jesus was a man approved of God: “You men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles and wonders and signs, which God did by him in the midst of you…” (Acts 2:22). Here Peter clearly taught that Jesus was a man, and that God did miracles “by him.”
It seems if the Trinity did exist, that when Peter had thousands of devout Jews gathered together on the Day of Pentecost would have been a good time to introduce it to them. But instead, Peter told the Jews that Jesus was the Messiah they had been expecting: a man approved of God.
Like Peter, Paul also taught that Jesus was a man. For example, when he was in Athens, Paul taught a crowd of unsaved Gentiles about Jesus Christ and said that God would judge the world “by the man whom He has appointed” (Acts 17:31). Paul never said or implied that Jesus was anything but a “man.” But especially since Paul’s Greek audience was polytheistic, it seems that if there was a Trinity that Paul would have taught it to the crowd. Whereas the Jews would have likely been very upset if someone taught there was a Trinity, these polytheistic Greeks would almost certainly not have been upset, so this would have been a perfect time to introduce the subject to people. But instead, Paul said that Jesus was a man appointed by God.
There are a number of other New Testament verses that state that Jesus was a man. For example, Romans says that a man, Adam, caused sin to enter into the world, and also that a man would have to redeem it from sin. Romans 5:15 (ESV) says, “For if many died through one man’s trespass, much more have the grace of God and the free gift by the grace of that one man Jesus Christ abounded for many.” Some theologians teach that only God could pay for the sins of mankind, but the Bible specifically says that a man must do it. The book of Corinthians makes the same point Romans does. It says, “For since by a man came death, by a man also came the resurrection of the dead” (1 Corinthians 15:21 NASB).
1 Timothy 2:5 says that it is Jesus, the man, who was the mediator between God and men. 1 Timothy 2:5 (ESV) says, “For there is one God, and there is one mediator between God and men, the man Christ Jesus.” This verse calls Jesus Christ a “man” even after his resurrection.
Trinitarian doctrine tries to explain the verses that say Jesus was a man by saying that he was a man, but he was also 100% God at the same time. But there are problems with that. One is that there is no single verse that says Jesus was both God and man. The God-man doctrine is built from many verses. Furthermore, scholars admit that there are only about eight verses in the entire New Testament that can be understood to say that Jesus is God, and every one of them can either be translated in a way that supports the Biblical Unitarian position, or disputed textually, or can be explained from the use of the word “God” in the culture.
In contrast, the clear verses where Jesus is said to be a “man,” such as when Peter or Paul taught their audiences that Jesus was a man appointed by God, are not disputed and in the context, there does not seem to be any good reason those men would not have said that Jesus was a God-man if in fact, that is what he is.
Actually, the book of Hebrews seems to clear up the subject when it says that when Jesus was on earth, he was made like us in every way: “Therefore he [Jesus] had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God” (Hebrews 2:17 ESV). This verse shows that Jesus was not both fully human and fully God at the same time. If he was, he would not be like us in every respect. If we believe that Jesus was a fully human man, this verse can be seen to be completely true, but if Jesus is fully God and fully human, it is confusing at best. None of us would have the doubts, worries, and fears, that we do if we were God. Saying that Jesus was made like us in every way is the Bible saying in a very straightforward way that Jesus was not “both God and human.”