Islam, Mormonism, the Jehovah's Witnesses, the liberal German Critical School, and others reject the idea of Jesus as God in human form. But John introduces Jesus to us in this way: "In the beginning was the Word [Jesus], and the Word was with God and the Word was God [theos] .. and the Word became flesh and lived among us" (John 1:1, 14). In this context, Jesus is the Word. And the Word is God in human form. Therefore, Jesus is God in human form. According to John, this concept was taught by Jesus about himself : "I and the Father are one" (10:30). Thomas confesses when he sees the resurrected Jesus, "my Lord [kurios] and my God [kurios]" (20:28). Matthew teaches the same concept: "His name shall be called, 'Immanuel,' [Hebrew literally "with us God"] (Matthew 1:22). For the writer of the book of Hebrews, God calls Jesus God: "Your throne, O God [theos] is forever and and ever" (Hebrews 1:8). Theos is the Greek word for God, and kurios is the Greek word for "Lord,", the word that is used to translated "Yahweh" in the Greek Old Testament. From these verses and others (compare Mark 12:36-37, "The Lord said to my Lord;" Colossians 1:15, "the image of the invisible God;" Philippians 2:6 ".. who being in the very nature God..") the early Church leaders built the Doctrine of the Incarnation. In Latin, carne means "flesh" and "in," of course, means "into." So, Jesus is God into flesh, and this teaching is found in multiple traditions that make up the New Testament. 

Let us note the following: 1) Immediately in Jesus' ministry, this teaching was rejected fiercely by his critics: "You, being a man, make yourself out  to be God" (John 10:33) and it led to his execution as a blasphemer: "We have a law and by that law he ought  to die because he made himself Son of God" (John 19:7). The Ebionites, a Jewish Christian group in the early Church rejected Jesus as God and accepted him only as a human Messiah. So, the rejection of Jesus as God in human form has a long history. 2) Christianity is monotheistic, also but Trinitarian. Jesus, as a Jew, stated the monotheism of Judaism in Mark 12:29: "Hear O Israel [the Shema - Jewish confession of faith in the One true God] the Lord our God is one Lord." Yet Jesus claimed to be God. His teaching about himself is later denied by Islam, the Jehovah's Witnesses, and others. He stated, "I and the Father are One" (John 10:30) - in essence not only in purpose, for the crowd tried to kill him in the next verse: they got the message! And he actually criticized his disciple Philip for not believing that he was the equivalent of the Father God in human form: "Have I been with you so long?.. He who has seen me has seen the Father.. Do you not believe that I am in the Father and the Father is in Me?" (John 14:9-10). Jesus opponents from the Jewish leadership attacked him for claiming to be God and successfully executed him for what they thought was blasphemy, the utterance of a spiritual lie: ".. but for blasphemy; and because you, being a man, make yourself out to be God" (John 10:33). Muslims claim that God cannot have a Son and that Jesus never claimed to be God, but every part of the New Testament tradition contradicts this claim: Jesus is regarded as God [Greek theos] in the Letter to the Hebrews (1:8), by Paul in his letters (Philippians 2:6; Colossians 2:9), by John (John 1:1, 14; 20:28), by the material in Matthew and Luke that is not in Mark ("Q": Matthew 11:27=Luke 10:22: nobody knows God the Father but Jesus). Bart Ehrman and others of the German Critical School claim Jesus was just a Rabbi who was made out to be Son of God by the later Church and the Gospels reflect this later "church theology" [Gemeindetheologie: But if Jesus was only a Rabbi, why did he ever get executed?] Jesus also taught that the Holy Spirit was a person, equal with him and the Father, who would continue his work of redemption in his disciples: "But He, when the Spirit of Truth comes, he will guide you into all the truth.. All things that the Father has are mine; therefore I said, that he takes of mine, and will disclose it to you" (John 16:15). Only God can lead into all the truth: "Sanctify them in the truth; your word is truth" (John 17:17), so the Holy Spirit is God, as Paul and others biblical writers declare: "The Lord is the Spirit" ( 2 Cor 3:17), ".. to lie to the Holy Spirit.. you have not lied to men but to God" (Acts 5:3-4).

The Incarnation, then, is Jesus humbling himself to become human for our redemption. Some other verses illustrate Jesus' temporary humble appearance on earth. Paul states, ".. though he was rich [in heaven before his incarnation], yet for your sake he became poor "[human, to die on the cross] (2 Cor 8:9). Jesus refers to his previous glory in heaven: "Father glorify me ..with the glory I had with you before the world began" (John 17:5). He stated to his disciples, "What if you see the Son of Man ascend to where he was before?" (John 6:62). The Christian teaching of the Incarnation is connected to the doctrine of the Trinity, the Deity of Christ and the Holy Spirit. This is not 1 + 1+ 1 = 3, as the Jehovah's Witnesses sometimes claim. It is not a "three headed monster" as some from Judaism have criticized. It is not a corrupt teaching, as Islam claims. It is the very teaching of Jesus about the nature of the one true God: three co-equal and co-eternal "persons" but one God - a truth that is actually beyond human comprehension. This is 1 x 1 x 1 = 1.