What does God do when a person believes the Gospel?
When a person believes the Gospel, God does it all: He places Himself in the believer and places the believer in Himself, granting the assurance of indwelling Holy Spirit and union with Christ. This is the criteria: having the Spirit of Christ means belonging to Him.
Les explains that the indwelling Holy Spirit is the criterion for being in Christ: if anyone does not have the Spirit of Christ, he is not His. He says you receive the Holy Spirit by believing the Gospel, and when you believe the Gospel, God does it all—He puts Himself in us, He puts us in Him, and we have this assurance. Les then points to 1 John 3:1, where believers are called the children of God because of the Father’s bestowed love, and consequently the world does not know them.