"I am telling you now before it happens, so that when it does happen you will believe that I am he. I tell you the truth, whoever accepts anyone I send accepts me; and whoever accepts me accepts the One who sent me." (John 13:19-20)

Jesus is saying this to his disciples following his stating that someone who was eating with them would be betraying him, as he quoted one of David's Psalms:
"'He who shares my bread has lifted up his heel against me.'" (John 13:18)
However, part of the first sentence is mistranslated. Jesus is not saying, "you will believe that I am he."

Who is the "he" that Jesus is referring to? This statement is not at all what the Greek being translated indicates.

The Greek phrase being used is πιστεύσητε ὅταν γένηται ὅτι ἐγώ εἰμι. Let's break this down:

The Greek word πιστεύω (pisteuō) means "to think to be true, to be persuaded of, to credit, place confidence in" or "to trust" according to the lexicon.

The Greek γίνομαι (ginomai) means "to become, i.e. to come into existence, begin to be, receive being" according to the lexicon, or to "arise, appear in history, come upon the stage" as in "of men appearing in public."

The Greek word ὅτι (hoti) means "that, because, since" according to the lexicon.

Then ἐγώ (egō) means "I" or "myself"

And εἰμί (eimi) means "to be, to exist, to happen, to be present" according to the lexicon.

Putting this together with the context, it is apparent that Jesus is saying something like:
"...you will trust in my appearance and who I am."
or simply:
"...you will trust in me and my appearance."
Putting this together with the first part of the sentence:
"I am telling you now before it happens, so that when it does happen you will trust in me and my appearance."
Why is trusting in Jesus' appearance so important? Jesus clarifies this in the next sentence:
"I tell you the truth, whoever accepts anyone I send accepts me; and whoever accepts me accepts the One who sent me."
So trusting in his appearance means to accept (or trust in) the One who sent Jesus: God.

While functionally correct, this second sentence is translated in such a way that seems to de-emphasize the "One" who sent Jesus. The translators did not even capitalize "One" in their translation (added here). Who were they thinking Jesus was sent by?

This illustrates the translators' lack of empowerment by God. These ecclesiastical scholars were paid salaries by their respective organizations to do this translating work. They were thus beholden to the interpretations of their organizations - which stem from the Nicene Creed dictated by a council hand-picked by the Roman emperor Constantine for political purposes - as Constantine wanted to control the Roman empire utilizing Christianity. The Creed thus interpreted Jesus' identity as being God in order to support a position that their religion could be the only correct religion. In doing this, they effectively forgot the Supreme Being.

With this interpretation and the resulting translations, these professional translators seek to support the "Jesus is God" interpretation of their respective organizations. This is despite the fact that Jesus himself did not support this interpretation, evidenced by his very statement here!

What would happen if these interpreters didn't support this interpretation? They would quickly lose their positions of authority and scholarship within their respective organizations. They would be ostracized. They would not be in such bad company, however. After all, Jesus was ostracized by the Jewish priests for not agreeing with their interpretations of the teachings of Moses, David and other prophets.

We should note that the Greek word λαμβάνω (lambanō), which is being translated to "accepts," also means "receives" or "to take with the hand, lay hold of, any person or thing in order to use it" according to the lexicon. The most appropriate translation to English, in this context, would be to (figuratively) "embrace."

Whether the word "accepts", "receives" or "embraces" is used, there is a double entendre being utilized here. Jesus is not talking about a physical embrace, acceptance or reception. He is talking about accepting his teachings. And by accepting his teachings, we are effectively accepting God Himself. Should we accept what Jesus is teaching and what Jesus' disciples taught, we are accepting Jesus, and thus accepting the Person who sent Jesus: The Supreme Being.

When someone is committed to their teachings as Jesus was, this is how we embrace that person: By accepting their teachings.

Jesus discusses two sender-messenger scenarios here: 1) Jesus sending someone; and 2) God sending Jesus.

And we have three possible receptions here: 1) Accepting someone who Jesus sends; 2) accepting Jesus; and 3) accepting God, who sent Jesus.

Jesus is tying them together, and thus saying that by accepting one of God's messengers, we are accepting God.

What ties the three together? Their teachings. They are all teaching the same thing. And what is their most important teaching?
"'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment." (Matt. 23:37-38)
This means that the Supreme Being wants us to return to our loving relationship with Him. He wants us to come home to Him. He does not need us: He is not dependent upon us. But He knows that we will only be truly happy when we return to Him. And He loves us; and thus wants us to be happy.

We were created to love and care for the Supreme Being. This is our nature and our purpose for existing. When we return to that state, we will be fulfilled. This is what the Supreme Person sent Jesus to tell us. By embracing this understanding, we are embracing the Supreme Being.

(For a translation of Jesus' statements from the Gospel of John without sectarian institutional influence, see the Devotional Translation  - translated from the original Greek texts.)