Great question! The question you’re asking really ultimately comes down to one of authority, who decides? Who decides what Jesus meant? Are we just supposed to argue back and forth with verses. Or did Jesus leave us with a better way?
Catholics believe he did. He left us with a Church who could interpret his words authoritatively, so we wouldn’t have to worry whose interpretations are correct. So the question is…which Church? For that we have to look to the only Church that’s been around since the time of the apostles. And that as a matter of history is the Catholic Church. And when we look at what the earliest Christian writers, those who were ordained by the apostles themselves or ordained by those who the apostles ordained, all the way up we see this constant truth taught, the divinity of Christ.
This is something the Church has always held, from the earliest days, even before the canon of the New Testament was officially put together, the Church was proclaiming and defending Jesus Christ as the Eternal Son, God in the flesh. It was so important many of them died for proclaiming it.
So that’s how we decide, we trust the Church’s ancient tradition. Something taught by the apostles themselves,.
Of course, the context and the words Jesus himself used help us see how he really couldn’t have been speaking any other way but literally. Some of the things he said and demanded of his followers are claims no creature, no matter how exalted or holy could properly make.
Things like saying the Son must receive the same honor as the Father, and if anyone doesn’t honor the Son, they don’t honor the Father(Jn 5:22-23).
That’s absolutely impossible and outright blasphemous for any mere man to say. Or demanding people to love him more than father or mother or wife and children, and to give up everything to follow him. No one but God deserves that kind of radical and complete devotion, as a Jew, Jesus would have recognized that. He constantly points people to himself, which is exactly the opposite of every other prophet or holy person who ever lived. They all tell people not to focus on them, but on God. Jesus doesn’t do that. That makes him either extremely prideful and arrogant, or crazy. He can’t just be a wise holy teacher and do that kind of stuff. Holy people don’t say those things.
And they definitely don’t use the Divine Name to refer to themselves like Jesus does in Jn 8:58.
But all these things don’t prove Jesus is God automatically. They lend credibility to the Church’s belief, but they are not the source of it. Her source is the witness of the apostles and the ones who were taught by them, all of whom professed the divinity of Christ. Because as you can see with this thread, we can get into semantic debates and swing verses back and forth until the cows come home. And not decide anything. There has to be an authority outside scripture, and that’s why we need the Church, and it’s the Church who ultimately gets to decide what Jesus meant.
And to answer your last question, the divinity of Christ is THE defining characteristic of Christianity. If someone denies it and calls themselves a Christian, that would be similar to someone calling themselves a Muslim yet denying Muhammed as the last and greatest prophet, it won’t work. (Obviously the cases aren’t exactly symmetrical, but you catch my drift
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