Biblical Christians do believe that Jesus was God; And Jesus Himself believed that He was God. Scripture supporting this is many, but here are a few examples:
"Jesus said to them, 'Most assuredly, I say to you, before Abraham was, I AM.'" --John 8:58
By relying on Old Testament references, we find out that "I AM" refers to the name of God Himself, Yahweh (often translated in English Bibles as LORD). The Jews were quite familiar with the idea that the Jehovah of the Old Testament is the eternally existent God. What was new to the Jews, was the identification of this designation with Jesus.
"Jesus answered... 'I and My Father are one.' Then the Jews took up stones again to stone Him. Jesus answered them, 'Many good works I have shown you from My Father. For which of those works do you stone Me?' The Jews answered Him, saying, 'For a good work we do not stone You, but for blasphemy, and because You, being a Man, make yourself God.'" --John 10:25-33
"Philip said to Him, 'Lord show us the Father, and it is sufficient for us.' Jesus said to him, 'Have I been with you so long, and yet you have not known Me, Philip? He who has seen Me has seen the Father; so how can you say, "Show us the Father"?'" --John 14:8,9
"He is the image of the invisible God, the firstborn over all creation. For by Him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through Him and for Him. And He is before all things, and in Him all things consist." --Colossians 1:15-17
Did Jesus exist?!
Cornelius Tacitus (A.D. 55-120) was a Roman historian who lived through the reigns of over half a dozen Roman emperors. He has been called the "greatest historian" of ancient Rome, an individual generally acknowledged among scholars for this moral "integrity and essential goodness." Tacitus's most acclaimed works are the Annals and the Histories. The Annals cover the period from Augustus's death in A.D. 14 to that of Nero in A.D. 68, while Histories begin after Nero's death and proceeded to that of Domitian in A.D. 96.
Writing of the reign of Nero, Tacitus alludes to the death of Christ and to the existence of Christians at Rome. His misspelling of Christ (Christus) was a common error made by pagan writers. Says Tacitus:
[size=2]"But not all the relief that could come from man, not all the bounties that the prince could bestow, nor all the atonements which could be presented to the gods, availed to relieve Nero from the infamy of being believed to have ordered the conflagration, the fire of Rome. Hence to suppress the rumor, he falsely charged with the guilt, and punished with the most exquisite tortures, the persons commonly called Christians, who were hated for their enormities. Christus, the founder of the name, was put to death by Pontius Pilate, procurator of Judea in the reign of Tiberius: but the pernicious superstition, repressed for a time, broke out again, not only through Judea, where the mischief originated, but through the city of Rome." (Annals XV, 44)
A possible allusion to Jesus' resurrection is in this account. It is distinctly possible, that, when Tacitus adds that "A most mischievous superstition, thus checked for the moment, again broke out," he is bearing indirect and unconscious testimony to the conviction of the early church that Christ who had been crucified had risen from the dead.
Another interesting sidelight about this passage from Tacitus: Pilate is not mentioned in any other pagan document which has come down to us.... And it may be regarded as an instance of the irony of history that the only surviving reference to him in a pagan writer mentions him because of the sentence of death which he passed upon Christ. For a moment Tacitus joins hands with the ancient Christian creed: "...suffered under Pontius Pilate."
Note that Tacitus's comments provide us with testimony by the leading Roman historian of his day, "independent confirmation that Jesus lived and was formally executed in Judaea in the reign of Tiberius and during Pilate's office as procurator (technically still a prefect, A.D. 26-36). That may not seem like much, but it is actually surprisingly useful in discounting two different theories which are sometimes advanced: first, that Jesus of Nazereth never existed; and secondly, that he did not die by the duly administered Roman death penalty."
Secular authorities-"pagan"-non-Christian, non-Jewish, and generally anti-Christian writers on Jesus' Historicity: Lucian of Samosata, Suetonius, Pliny the Younger, Thallus, Phlegon, and Mara Bar-Serapion.
Jewish References to Jesus' historicity: The Babylonian Tulmud
Christian Sources for Jesus' Historicity (Post-Apostolic Writers): Clement of Rome, Ignatiius, Quadratus, The Epistle of Barnabas, Aristides, Justin Martyr, and Hegesippus.
Additional Sources for Christianity: Trajan, Macrobius, Hadrian, Antoninus Pius, Marcus Aurelius, Juvenal, Seneca, and Hierocles.[/size]