The phrase “not of this world” comes from John 18:36 where Jesus says, “My kingdom is not of this world. If my kingdom were of this world, my servants would have been fighting, that I might not be delivered over to the Jews. But my kingdom is not from the world.” In context, Jesus is speaking to Pilate, assuring the governor that He was not leading a political revolution to overthrow Rome; rather, He was leading a spiritual movement that would change the hearts of people for eternity.
Earlier, Jesus had prayed, “I have given them your word, and the world has hated them because they are not of the world, just as I am not of the world” (John 17:14). This verse gives us a clue as to why we are “not of this world”—because Jesus isn’t. When we are born into the family of God, we “participate in the divine nature and escape the corruption in the world caused by evil desires” (2 Peter 1:4 ). We walk as Jesus walked (1 John 2:6), and He was out of step with this world’s system, to say the least. This world relies on what it can see, but we walk by faith, not by sight (2 Corinthians 5:7).
We have a perspective not of this world. We, like Moses, endure because we see the unseen (Hebrews 11:27). Like faithful Abraham, the Christian lives “as in a foreign land … looking forward to the city that has foundations, whose designer and builder is God” (Hebrews 11:9-10). Like Jesus, we can be shown “all the kingdoms of the world and their glory,” and, like Jesus, we can refuse it all (Matthew 4:8-11).
We have treasures not of this world. We seek “a treasure in the heavens that does not fail, where no thief approaches and no moth destroys” (Luke 12:33). Our riches are not material but eternal, “kept in heaven” (1 Peter 1:4). The world wants it all now; we can wait for it.
We have weapons not of this world. Our enemy is spiritual, as are our weapons and tactics of battle. “For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds” (2 Corinthians 10:4).
We have power not of this world. We place our trust not in our own strength or earthly might but in the Spirit of God (Zechariah 4:6). “Some trust in chariots and some in horses, but we trust in the name of the LORD our God” (Psalm 20:7). We live with a paradox: “When I am weak, then I am strong” (2 Corinthians 12:10) because “the one who is in you is greater than the one who is in the world (1 John 4:4).
We have peace not of this world. Our peace in any situation comes straight from our Lord, the Prince of Peace: “Peace I leave with you; my peace I give to you. Not as the world gives do I give to you” (John 14:27). Nothing can take that away.
We have a home not of this world. “Our citizenship is in heaven” (Philippians 3:20). Those who have lived and died in faith “acknowledged that they were strangers and exiles on the earth” (Hebrews 11:13). This world was not their home, nor ours. We look forward to the Father’s house, where there are “many rooms” (John 14:2). “For here we have no lasting city, but we seek the city that is to come” (Hebrews 13:14).
Being “not of this world” means we have a higher, that is, a heavenly calling, purpose, and destination. This world and its priorities are fading away, but the one who does the will of God lives forever (1 John 2:17). “What counts is the new creation” (Galatians 6:15 )
When we read of the “world” in the New Testament, we are reading the Greek word cosmos. Cosmos most often refers to the inhabited earth and the people who live on the earth, which functions apart from God. Satan is the ruler of this “cosmos” (John 12:31; 16:11; 1 John 5:19). By the simple definition that the word world refers to a world system ruled by Satan, we can more readily appreciate Christ’s claims that believers are no longer of the world—we are no longer ruled by sin, nor are we bound by the principles of the world. In addition, we are being changed into the image of Christ, causing our interest in the things of the world to become less and less as we mature in Christ.
Believers in Jesus Christ are simply in the world—physically present—but not of it, not part of its values (John 17:14-15). As believers, we should be set apart from the world. This is the meaning of being holy and living a holy, righteous life—to be set apart. We are not to engage in the sinful activities the world promotes, nor are we to retain the insipid, corrupt mind that the world creates. Rather, we are to conform ourselves, and our minds, to that of Jesus Christ (Romans 12:1-2). This is a daily activity and commitment.
We must also understand that being in the world, but not of it, is necessary if we are to be a light to those who are in spiritual darkness. We are to live in such a way that those outside the faith see our good deeds and our manner and know that there is something “different” about us. Christians who make every effort to live, think and act like those who do not know Christ do Him a great disservice. Even the heathen knows that “by their fruits you shall know them,” and as Christians, we should exhibit the fruit of the Spirit within us.
Being “in” the world also means we can enjoy the things of the world, such as the beautiful creation God has given us, but we are not to immerse ourselves in what the world values, nor are we to chase after worldly pleasures. Pleasure is no longer our calling in life, as it once was, but rather the worship of God.
source: Compelling Truth/ Gotquestions
Building 429 – Where I Belong
https://youtu.be/Hoq44rFNbhY