How can Jesus be God if 'God is not man' according to Numbers 23:19?

from the old testament

• In Numbers 23:19, God was being contrasted to human beings in terms of character and reliability: “God is not man, that he should lie, or a son of man, that he should change his mind. Has he said, and will he not do it? Or has he spoken, and will he not fulfill it?” It’s a rhetorical statement that basically says, “God is not unfaithful like sinful men and women!” Similar statements appear elsewhere, such as in 1 Samuel 15:29 and Hosea 11:9, where God is again contrasted with human weakness to show how He is not like us.
• The Old Testament also hints that God would one day draw near to His people uniquely and humanly. Scripture speaks of a coming Messiah who would be both divine and human (Isaiah 9:6), a promised Davidic king whose throne would be established forever (2 Samuel 7:12–13; Isaiah 9:7), and a suffering servant who would bear the sins of many (Isaiah 53:4–6). These promises prepared God’s people to expect a Redeemer who would act personally on their behalf. Thus, when the New Testament describes the Son of God adding on humanity, it was not a new invention, but the fulfillment and clarity of themes already present in Scripture.

from the new testament

• The Old Testament hinted that God would provide a solution to the problem of human sin and guilt. John, referring to Jesus as “the Word,” explained that “the Word was God” and that this same Word “became flesh and dwelt among us” (John 1:1, 14). The Son of God was always divine, but at a point in time, He added on humanity.
• Paul spoke about this same event, saying, “though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant, being born in the likeness of men. And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross” (Philippians 2:6–8).
• Jesus’ divine character remained unchanged because “in him the whole fullness of deity dwells bodily” (Colossians 2:9). Like the God described in Numbers 23:19, Jesus was truthful and unchanging (John 8:29; Hebrews 13:8). At the same time, in His humanity, He lived without sin, being “tempted as we are, yet without sin” (Hebrews 4:15; 1 Peter 2:22).
• Numbers 23:19 contrasted God with sinful humankind.Jesus, being the perfect God-man, was the first (and only) man who was equal to God’s character (John 14:9).

implications for today

Who do you look like? Is your nose your father’s and your forehead your mother’s? Maybe your hair color is your great-grandmother’s and your musical talent is from your grandfather. Like ingredients thrown into a soup, our traits are from many sources. Most of all, though, we’re made in the image of God. Yet despite being image bearers , we are marred by sin. Numbers 23:19 is one of many reminders in Scripture as to why we are not like God. While He cannot lie (Titus 1:2), we frequently do. While He is faithful, we are not. While He is perfect, we are far from it.

That is why Jesus matters so much. To save us, God did not relax His standards. Instead, He sent His perfectly righteous Son to add on humanity and then live it as it was meant to be lived. Jesus fully shared our humanity, but He did not share our sin. Where every other human has fallen short, He obeyed perfectly. Where we lie and change, He remained faithful and true. In Him, God’s character was displayed in a human life.

Considering all this should make us ever more grateful that Jesus deigned to sacrifice Himself for us. We look forward to eternal life because He lowered Himself to enter our world to die for us.