Oh for.People believed all sorts of things..
The church clergy "chose" what to believe, and it was endorsed politically by the Roman Empire.
They outlawed other creeds .. particularly those that were closer to Judaism.
The Gospels chosen were the earliest written and predated the Roman conversion to Christianity by over 200 years. The earliest Gospels, that is, the ones in the NT, affirm Jesus' divinity as I quoted above. No Roman figurehead had anything whatsoever to do with this.