This is a line from an old hymn and it was a popular idea in the church for a long time. A related popular expression is that we are to be ‘in the world but not of it.’ Regardless of what we think it is important to see what the scriptures have to say regarding the issue so we can respond with a right heart.
Jesus did say clearly that His kingdom was not of this world
36 Jesus answered, “My kingdom is not of this world. If My kingdom were of this world, My servants would fight, so that I should not be delivered to the Jews; but now My kingdom is not from here.” John 18:36 (NKJV)
Note that Jesus spoke this prior to His crucifixion and resurrection. After His resurrection in The Great Commission, He spoke differently.
18 And Jesus came and spoke to them, saying, “All authority has been given to Me in heaven and on earth. 19 Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age.” Amen. Matthew 28:18-20 (NKJV)
Here Jesus directs us to go under His authority to extend His kingdom in the earth. He wants us to contend for what He achieved through His sacrifice for us. I raise this issue because for much of the 20th Century the dominant theology in much of the evangelical community was the idea that things would get worse and worse for the church. Jesus would then come and rescue a weakened persecuted church from the ravages of the world |(the pretribulation rapture) and punish the evildoers while the church watched from heaven.
Aside from the above seeming to be a rather ‘unkind’ theology, I personally have never been able to find it in scripture and it seems to be at odds with The Great Commission. In fact, Jesus told us something else as well, a sign of His return.
14 And this gospel of the kingdom will be preached in all the world as a witness to all the nations, and then the end will come. Matthew 24:14 (NKJV)
Whatever our ideas are, Jesus seems to have the idea that the gospel is to spread to all nations all over the earth. While His kingdom is not ‘of’ this world it is designed to spread in the world and influence culture prior to His return. I do not have all of my end time theology settled. What I do have settled is that I need to heed Jesus over popular theology and do my part to live in and out of His kingdom while I am here and able. After all, when the end does come He is not taking us out of the world, He is bringing the fullness of His kingdom to this world, a renewed earth. The world will be our home.
1 Now I saw a new heaven and a new earth, for the first heaven and the first earth had passed away. Also there was no more sea. 2 Then I, John, saw the holy city, New Jerusalem, coming down out of heaven from God, prepared as a bride adorned for her husband. Revelation 21:1-2 (NKJV)