What does it mean if someone does not have the Spirit of Christ?
If someone does not have the Spirit of Christ, which is the Holy Spirit, that person is not His—they do not belong to Christ. The indwelling Holy Spirit is the criteria: having Him means you are in Christ, and He is received by believing the Gospel.
Les explains that the Spirit of Christ is the Holy Spirit. If anyone does not have the Spirit, he is not His—it is that simple. The criteria is the indwelling Holy Spirit: if you have Him, you are in Christ. How do you get the Holy Spirit? By believing the Gospel. When you believe, God does it all—He puts Himself in us, He puts us in Him, and we have this assurance. Les then takes listeners back to 1 John 3:1, where believers are called the sons or children of God, and as a result, the world does not know them.
But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.