Early Christian leaders wrote thousands of pages in letters to one another combatting heretics. Most of these works survive. If you look at the writings of first disciples that the apostles trained and their disciples, it is easy to figure out.
Like this:
Anyone who ignores the clear evidence in the bible, the early christian leaders writings, and common sense is welcome to their delusion.
If Jesus wasn't God, how did he resurrect himself from the dead like he predicted? If you say, oh, he didn't God resurrected him, the the bible wrong and Jesus is a liar and the greates con artist who ever lived.
In John 10:17–18 Jesus says something that no mere mortal could ever say: “I lay down my life—only to take it up again. No one takes it from me, but I lay it down of my own accord. I have authority to lay it down and authority to take it up again.”
No one else in the history of the world has ever had the authority both to lay down his life and to raise it up again.