The phrase not of this world is found in John 18:36 where Jesus says that His kingdom is “not of this world.”
The context of Jesus’ statement is His interrogation by Pontius Pilate during one of His trials. Pilate had summoned Jesus into the palace and, in trying to ascertain the charges against Him, basically asked Jesus to incriminate Himself. The conversation went like this:
Pilate asked, “Are you the king of the Jews?”
Jesus responded with a question of His own: “Is that your own idea, or did others talk to you about me?”
“Am I a Jew?” Pilate replied. “Your own people and chief priests handed you over to me. What is it you have done?”
Jesus said, “My kingdom is not of this world. If it were, my servants would fight to prevent my arrest by the Jewish leaders. But now my kingdom is from another place.”
“You are a king, then!” said Pilate.
Jesus answered, “You say that I am a king. In fact, the reason I was born and came into the world is to testify to the truth. Everyone on the side of truth listens to me” (John 18:33–37).
When Pilate asked Jesus if He was a king, Pilate was thinking of a political position and that Jesus was possibly guilty of sedition against Caesar. In saying that His kingdom is “not of this world,” Jesus denied that He was a king in that sense—and His words were proved by the lack of any subjects fighting to release Him (John 18:36).
But Jesus does not deny His kingship wholly; He has a kingdom, but it is “from another place” (John 18:36). He says He had “come into the world” (John 18:37), with the clear implication that He was from some place other than this world (cf. John 3:3). His kingdom is heavenly and extends over the hearts and minds of His subjects. It does not originate in this world: “His royal power and state are not furnished by earthly force, or fleshly ordinances, or physical energies, or material wealth, or imperial armies” (The Pulpit Commentary, Vol. 17, Hendrickson Pub., 1985).
As His followers, Christians are members of His kingdom, which is “not of this world.” We know that “our citizenship is in heaven” (Philippians 3:20). As a result, we “put aside the deeds of darkness and put on the armor of light” (Romans 13:12). We wage spiritual battle, but “the weapons we fight with are not the weapons of the world” (2 Corinthians 10:4). We “seek first his kingdom and his righteousness” (Matthew 6:33). And we rest in the knowledge that our King gives us eternal life: “The world and its desires pass away, but whoever does the will of God lives forever” (1 John 2:17).
We are on earth for now, but our earthly lives are nothing but a vapor in comparison to eternity (James 4:14). “This world in its present form is passing away” (1 Corinthians 7:31). The sufferings and trials of this world are part of life. But, in remembering that we are “not of this world,” we know that such things are just for a little while (1 Peter 5:10). The knowledge that we are not of this world gives Christians hope even in the darkest times (1 Peter 1:6 –9). This broken place is not where we ultimately belong, and it is not where we will stay (Hebrews 13:14). “We are receiving a kingdom that cannot be shaken” (Hebrews 12:28).
Christians, as part of Jesus’ kingdom, are not of this world. We have been adopted as heirs of heaven by God Himself, and that is where our citizenship is (Titus 3:7). Until our King returns, we wait (Titus 2:13), and we hope (Romans 5:5), and we do what we can to bring others into the “not of this world” relationship with Jesus Christ.