13:19a

I am telling you now before it happens: This clause indicates that Jesus told the disciples that someone would betray him before it occurred (happened). Judas had not yet betrayed Jesus, but Jesus told the disciples that he would. Here are other ways to translate this clause:

I tell you this now, before the event (Revised English Bible)

13:19b

so that: The conjunction that the Berean Standard Bible translates as so that means “in order that.” It introduces the purpose Jesus had in telling them that Judas would betray him before it happened.

when it comes to pass, you will believe that I am He: The clause when it comes to pass refers to when one of Jesus’ disciples would betray him. When what Jesus predicted occurred (happened), his disciples would believe that Jesus was the Messiah and even God himself. They would believe that because predicting the future is something that God does.

when it does happen you will believe that I am He (New International Version)
-or-
so that when it happens you will believe that I AM the Messiah (New Living Translation (2004))
-or-
so that when they do happen, you may believe that I am the one I claim to be (Phillips’ New Testament in Modern English)

you: The pronoun you is plural and refers to all of the disciples.

believe: Here this word refers to believing that something is true, that “I am he.”

I am He: The Greek expression that the Berean Standard Bible translates as I am He is more literally “I am.” There are two ways to understand this expression in this context:

(1) It refers to Jesus’ own claims (what he declared) about himself. For example:

I am the one I claim to be. (New International Version (1984))

(New International Version (1984), Revised English Bible, God’s Word, Contemporary English Version)

(2) It refers to the holy name of God, “I am who I am.” See Exodus 3:14, where God revealed himself to the people of Israel by this name. This interpretation says that Jesus claimed to be God. For example:

I Am Who I Am (Good News Translation)

(Good News Translation, New American Standard Bible, New Jerusalem Bible)

The King James Version, English Standard Version, NIV2011, New Century Version, NET Bible, Revised Standard Version, and New Revised Standard Version can be understood either way. The New Living Translation (2004) includes both ideas. It is probably good to translate this clause so that both interpretations are possible. Jesus probably implied (but did not state) that he was God and was from above. Because Jesus did not make it very clear that he was God here, you should not be very clear either. See how you translated this same expression in 8:24. Here are other ways to translate this clause:

I am who I am (NIV2011)
-or-
I AM the Messiah (New Living Translation (2004))

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