On the contrary, they would have considered it blasphemous, and they did, which is precisely one of the main reasons they killed him.
Joh 5:18 This was why the Jews were seeking all the more to kill him, because not only was he breaking the Sabbath, but he was even calling God his own Father, making himself equal with God. (ESV)
Joh 8:58 Jesus said to them, “Truly, truly, I say to you, before Abraham was, I am.”
Joh 8:59 So they picked up stones to throw at him, but Jesus hid himself and went out of the temple. (ESV)
Joh 10:33 The Jews answered him, “It is not for a good work that we are going to stone you but for blasphemy, because you, being a man, make yourself God.” (ESV)
Because it is biblical. It is the most important truth about who Jesus is and central to the gospel and salvation.
There are the teachings that there is only one God, Jesus is the Son of God, that he is God, but that he isn't the Father. It's putting the pieces together, taking God's revelation as a whole, which is what we must be doing.
Which, as I have pointed out, isn't relevant since they couldn't even understand that the Messiah was not going to come and vanquish their enemies. They completely missed that the Messiah was going to die and rise again for the salvation of all.
That Jesus is truly God in addition to being truly man is taught throughout the NT, even by Jesus himself, as I have given above.
When did they supposedly invent the deity of Jesus? There are significantly more than 8 verses.
It is. It's in numerous places in the NT.
Again, it's found by taking
the entire revelation of God into account, not by taking one verse at a time, which is what anti-Trinitarians typically do. Besides, on what basis is a doctrine declared true because there is a "whole paragraph or chapter teaching that we should believe," especially when such divisions came later and were somewhat arbitrary? Good theology and doctrinal development are always done by taking
all the relevant verses and passages into account.
Joh 20:28 Thomas answered him, “My Lord and my God!” (ESV)
Thomas confessed that Jesus was both his Lord and his God, without any rebuke from Jesus, so that makes me think that we should too. John begins and ends his gospel with the clear teaching of the deity of Jesus:
Joh 1:1 In the beginning was the Word, and the Word was with God, and the Word was God.
Joh 1:2 He was in the beginning with God.
Joh 1:3 All things were made through him, and without him was not any thing made that was made.
...
Joh 1:10 He was in the world, and the world was made through him, yet the world did not know him.
...
Joh 1:14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.
...
Joh 1:18 No one has ever seen God; the only God, who is at the Father's side, he has made him known. (ESV)
And, John shows the deity of Jesus throughout his gospel, some of which I have already given.
But, that isn't true. The deity of Christ is found very early in Christian writings. Take Ignatius, for example, who often speaks of Jesus and the Son as being God: "Jesus Christ, our God" (Ephesians 1); "For our God, Jesus Christ, was, according to the appointment of God, conceived in the womb by Mary, of the seed of David, but by the Holy Ghost" (Ephesians 18); "God Himself being manifested in human form for the renewal of eternal life (Ephesians 19); "the Church which is beloved and enlightened by the will of Him that willeth all things which are according to the love of Jesus Christ our God . . . in Jesus Christ our God" (Romans 1); "For our God, Jesus Christ" (Romans 3); "Look for Him who is above all time, eternal and invisible, yet who became visible for our sakes; impalpable and impassible, yet who became passible on our account; and who in every kind of way suffered for our sakes" (Polycarp 3). He also has some very Trinitarian language, "as being stones of the temple of the Father, prepared for the building of God the Father, and drawn up on high by the instrument of Jesus Christ, which is the cross, making use of the Holy Spirit as a rope" (Ephesians 9).
Or, look at what Polycarp, said to have been a disciple of John, writes in his letter to the Philippians:
'2 Now may God and the Father of our Lord Jesus Christ, and the "eternal Priest" himself, Jesus Christ, the Son of God, build you up in faith and truth, and in all gentleness, and without wrath, and in patience, and in longsuffering, and endurance, and purity, and may he give you lot and part with his saints, and to us with you, and to all under heaven
who shall believe in our Lord and God Jesus Christ and in his "Father who raised him from the dead"' (12:2).
https://www.earlychristianwritings.com/text/polycarp-lake.html
Also, when praying at his martyrdom, he reportedly stated: "I praise You for all things,
I bless You, I glorify You, along with the everlasting and heavenly Jesus Christ, Your beloved Son, with whom, to You, and the Holy Ghost, be glory both now and to all coming ages. Amen." (The Martyrdom of Polycarp, 14:3).
https://www.earlychristianwritings.com/text/martyrdompolycarp-lightfoot.html
Those are early to mid second century.
No, I don't, because worship of Jesus and claims of his deity started in the NT, which is why those have continued throughout Church history. The doctrine of the Trinity simply best takes into account and makes the most sense of all that the Bible reveals about the nature of God and Jesus.
That was also the Church that gave us our canon. Just because it took time to develop a more robust Trinitarian doctrine and theology, and just because there are other disagreeable doctrines developed, doesn't mean that the Trinity is false or unbiblical. It's a non-sequitur to make such an association.