O righteous Father, the world hath not known Thee: but I have known Thee, and these have known that Thou hast sent Me.
And I have declared unto them Thy Name, and will declare it: that the love wherewith Thou hast loved Me may be in them, and I in them.
An unrighteous world cannot know Who the Father is. Only the righteous Son fully understands the Father, and what is about to take place.
This, the greatest love story ever told, is a story of the so great love of the Father for His Son, and for the whole of mankind. Jesus knew that He had been sent from the Father. His disciples knew that He had been sent from the Father. They knew that Jesus had often declared that He and the Father were One. The fulfillment of that declaration was about to begin, and the disciples themselves did not yet fully understand all that was about to take place.
Jesus did. He asked, in this ending to His High Priestly prayer, that the same love of the Father which was in Him would reveal itself in His disciples, who would then begin the process of sharing the love of God with all of humankind.
First, though, they had to get through the next few hours of horror.