I have met a lot of skeptics and cultists who assert that Jesus never claimed to be God. Rather, they say he referred to himself as the son of man. It is not just skeptics and cultists who are troubled by this issue. I have met just as many Christians who ask, “If Jesus is the Son of God, why did he so consistently refer to himself as the son of man?” The common follow-up question is how can I be certain that Jesus is really God and that the Trinity is a correct doctrine?
Whole books have been written answering these questions. My goal here is to provide three brief yet adequate answers that you can quickly share with people expressing these kinds of challenges, concerns, and doubts.
First, while Jesus in the gospels almost always referred to himself as the “son of man,” there is at least one occasion where he explicitly claims to be God. The gospel text is John 8:58, where Jesus declares to the Jewish religious leaders, “Before Abraham was born, I AM!” Here, Jesus assumes the name God had assigned to himself in Exodus 3:14, “I AM who I AM. This what you are to say to the Israelites: I AM has sent me to you.” The Jewish religious leaders clearly understood that Jesus was claiming to be God, and it is evidenced by the fact that they attempted to stone him to death for his act of “blasphemy.”
Second, the Old Testament in Jeremiah 23:6 assigns the name YHWH (I AM) to the righteous Branch, the King, who will come from the lineage of David. Jesus in several places in the gospel claims to be this righteous Branch and King.
Third, Jesus is making a special theological point about his deity in calling himself the son of man in the gospels. This point becomes clear in examining the New Testament. For every New Testament passage referring to Jesus Christ that happened chronologically after the first day of Pentecost (Acts 2:1–41), Jesus is always referred to as the Son of God and never as the son of man. Conversely, in the gospels, Jesus consistently calls himself the son of man and never the Son of God.
The New Testament makes the same kind of demarcation for the human followers of Jesus Christ. Jesus’ followers before the first day of Pentecost are always called sons of men or children of men and never as sons of God. Jesus’s followers after the first day of Pentecost are always called sons of God and never as sons of men (for biblical references, see appendix c in Navigating Genesis).
The theological point here is this: it is not until Jesus of Nazareth dies on the cross to atone for the sins of all humanity, is raised bodily from the dead, and sends the Holy Spirit to permanently indwell and spiritually baptize his followers, does he complete his role as the Son of God, the second person of the triune God. Likewise, not until Jesus’ followers receive the baptism of the Holy Spirit do they become sons of God.
This theological point is affirmed by the observation that nowhere in the Old Testament is a human follower of God referred to as a son of God. Even Daniel, as “highly esteemed” (Daniel 10:11, 19) as he was for his righteousness before God was called “son of man” (Daniel 8:17). The one Old Testament exception is Hosea 1:10 where God promises that a time will come in the future when some of the Israelites will become “children of the living God.” This prophecy was fulfilled on the first day of Pentecost described in Acts 2.
Anyone desiring a more in-depth and thoroughly documented answer will find it in my book Navigating Genesis. It is in chapter 14 and appendix c.