The drama here is amazing. It’s the epitome of “cloak and dagger” stuff. The deceit and the interplay between the individuals is stunning. “What is the message for the recipients of this Gospel? What is the message for us?” Thankfully we don’t have to guess at the intention of the Holy Spirit.
John 13:19 (ESV)
19 I am telling you this now, before it takes place, that when it does take place you may believe that I am he.
Does that not line up perfectly with John’s Gospel aim? “but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.” (John 20:31, ESV)
This amazing drama serves this noticeably clear purpose: When the events take place (namely the betrayal of Jesus) this confirms that what Christ said is true, therefore confirming that He is God. When God affirmed His Deity to Israel, He spoke through the prophet Isaiah:
“I am the LORD; that is my name; my glory I give to no other, nor my praise to carved idols. Behold, the former things have come to pass, and new things I now declare; before they spring forth I tell you of them.”” (Isaiah 42:8–9, ESV)