To say that Jesus had a real human body does not mean that He wasn't God. The opposite is true. When Jesus entered this world, He was fully man and fully God at the same time.
John the Apostle was clear that if you are a genuine believer, what you believe about Jesus matters. A true believer in Jesus will be shown by certain distinguishing marks: faith, obedience, love. Here we're talking about the mark of faith. True followers of Jesus will be shown by their faith. Believing that Jesus is God really matters.
You can trust that Jesus was (and is) also fully God.
Not only was it clear to John, who was there with Jesus, that He had a real human body, it was also clear that He was the divine Son of God. He says it this way in 1 John:
And we have seen and we testify that the Father has sent His Son as the world’s Savior. Whoever confesses that Jesus is the Son of God—God remains in him and he in God. (1 John 4.14-15, HCSB)
So believing that Jesus is God really matters. It matters that we believe that He was really a man, and that He was really God—at the same time.
It is not merely that God the Father saw a remarkable and holy man named Jesus from Nazareth, and then decided to adopt him. That is a heresy known as Adoptionism. Those who take this wrong view would essentially say that Jesus was such an amazing man on His own, that God saw Him from heaven, decided that Jesus would make a great Savior, adopted Him as His son, and then gave Him power and authority. This view completely contradicts key sections of Scripture.
Jesus was indeed born of God into this world, after the Holy Spirit overshadowed Mary (Luke 1.35; Matthew 1.18), but that does not mean He was created. Jesus, the eternal second person in the Trinity, was already with God the Father when they began creating (John 1.1-3).
The Apostle John simply affirms Him as the anointed God-man, the Messiah. And whoever believes in Him as the Messiah will be saved:
Everyone who believes that Jesus is the Messiah has been born of God, and everyone who loves the Father also loves the one born of Him. (1 John 5.1, HCSB)
Many centuries earlier, Isaiah had prophesied that His name would be Immanuel, translated God With Us. And that is exactly who He is.
You can trust that Jesus had a real human body, and that He was and is also fully God. When you do, it's a mark of faith.
