But you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. Now if anyone does not have the Spirit of Christ, he is not His. And if Christ is in you, the body is dead because of sin, but the Spirit is life because of righteousness.
We previously covered Romans 8:14-15, which explains that those who are led by the Spirit of God are the sons of God. The gift of the Holy Spirit gives us the start of a new life as a child of God.
Repentance shows our deep desire and commitment to turn from and resist the way of sin that comes naturally to us as fleshly human beings. Baptism represents the death of the old man, and the gift of the Holy Spirit through the laying on of hands marks the start of a new spiritual life. This verse shows that anyone who doesn’t have the Spirit is not yet Christ’s—not yet a real Christian.
For more about the conversion process and how Jesus Christ lives in a converted Christian, see “Christ in Us: How Does He Live in You?”