In the early days of Christianity, how one answered this question was a serious matter, because the Church regarded a denial of the divinity of Jesus Christ as anti-Christ, as we read in 2nd John 1:7, "Many deceivers who do not acknowledge Jesus Christ as coming in the flesh have gone out into the world. Any such person is a deceiver and an Anti-Christ."
To affirm the divinity of Jesus, the Council of Nice and subsequent councils, particularly the Fourth Lateran, stated that the Word, as in John 1:1, is consubstantial, meaning of the same substance with God and the Holy Spirit, thus establishing the divinity of Jesus Christ as the Word incarnate.
Soon afterward, questions arose regarding when did the Word incarnate Jesus Christ. Did the Word incarnate him when he was being put in Mary's womb as a fertilized human egg? Did the incarnation occur during his gestation period as a fetus? Did the incarnation occur at the time of his birth? Or did it occur at a particular time during the course of his 33 years on earth?
Attempts to answers these questions, and affirm emphatically that God, or a part of God did not die on the cross brought into the conversation the doctrine of groups like the Ebionites, the Theodotians, the Artemonites and the Photinians that said Jesus Christ is not God, but a man uniquely enlightened by divine wisdom; as did the Gnostic theory that said Jesus Christ was an eon emanating from the Divine Being.
On their part, the Theistic, Pantheistic Sabellians and Patripassians argued that Jesus Christ was the manifestation of the Divine Being, the Word incarnate, but not made of the same substance as God and the Holy Spirit.
The Roman Catholic Church unequivocally disagrees with those doctrines. The church supports the doctrine established by the Council of Chalcedon and the Second Council of Constantinople that said both the divine and the human nature of Jesus Christ are physically united as one (New Advent Catholic Encyclopedia, Volume XIV).
This definition of the divinity of Jesus, effectively puts outside the traditional Christian doctrine the views of the Docetist Marcion, Priscillianists, Valentinians and the Appollinaris whose members granted Jesus Christ an ostensible, rather than an actual body. In their minds, they saw Jesus as an idea, rather than a physical person.
To the above, add renown thinkers like Kant, Jacobi, Fichte, Schelling and Hegel, all of whom saw Jesus not as a historical person, but a religious ideal, as were the Socinians and writers like Ewald and Schleiermacher who professed that Jesus Christ is a perfect revelation of God, but agreed with Pontius Pilate that Jesus is a man, not God (John 19:5).