How can we know the words of Jesus in the four gospels are really His since they weren't written while He was alive?

John 17:1 - 26

ESV - ¹ When Jesus had spoken these words, he lifted up his eyes to heaven, and said, "Father, the hour has come; glorify your Son that the Son may glorify you. ² Since you have given him authority over all flesh, to give eternal life to all whom you have given him.

Clarify • Share • Report • Asked February 26 2018 • Anonymous