Proof from even Non-Christians that Christians Taught Jesus is God
Even the enemies of Christianity bear witness that Christians worshipped Jesus as God.
Pliny the Younger (governor and persecutor of Christians in 112 A.D.) "They [Christians] were in the habit of meeting on a certain fixed day before it was light, when they sang in alternate verses a hymn to Christ, as to a god, and bound themselves by a solemn oath, not to do any wicked deeds…"
Lucian (2nd century satirist) "The Christian, you know, worship a man to this day - the distinguished personage who introduced their novel rites, and was crucified on that account…."
This is significant, because an official Roman query states that Christians worshipped Christ as God as early as 112 A.D. Thus, if a Muslim wishes to say that worshipping Jesus as God was an "error" introduced later, this was introduced prior to 112 A.D. By the way, the apostle John wrote the book of John around 90 A.D., and he lived a while after that. Again, the first fragment of John we have today that mentions Christ as a king (an un-Islamic term) is the John Rylands fragment, 117-138 A.D.
Conclusion
Early Bible manuscripts show, and the writings of followers and even foes of Christ confirm, that Jesus taught that He was God, demonstrated He was God, and accepted worship. The evidence stretches from c.112 A.D., up through Mohammed's time, when 'Aisha reports that Mohammed was taught the Gospels in Arabic (Bukhari 4:605). Jesus was taught the Gospel according to Sura 3:48, and Christians are the people of the Gospel in Sura 5:46.
But you might say that the Bible is corrupted. If so, then where does that say that in the Koran? You will find verses that man perverted the teachings but nowhere does it reveal nor will you ever find it saying that the Bible was corrupted.
But if by chance you say that the Koran does not directly say the Bible was corrupted but it's still corrupted because that is what you believe...then why are you asking the question 'where does it say that Jesus is God' when you can't even directly claim (prove) that the Bible was corrupted...conclusively...without a doubt.