4 That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit. (Romans 8:4 KJV)
William Burkitt’s Commentary
Apostle Paul here assigns another end and cause for which God sent his Son into the world; namely, to do what the law commanded, as well as to suffer what the law threatened; perfectly to fulfil the righteousness of the law for us, which it was impossible for us to do for ourselves; for the sake of which we are accounted righteous in the sight of God.
Learn hence, 1. That our Lord Jesus Christ, being made under the law, fulfilled the law; whatsoever the law did or could demand is fully satisfied and fulfilled by Christ.
Learn, 2. That Christ having fulfilled the law on our behalf, whatever can be required of us by way of punishment is discharged likewise.
Learn, 3. That though the righteousness of the law be fulfilled for us by Christ, yet the gospel-righteousness must be performed by us ourselves.
Christ has answered the demands of the law for us, but will never fulfil the conditions of the gospel for us. We must repent ourselves and obey ourselves, or Christ’s obedience will profit us nothing; none can safely or comfortably pretend to have an interest in Christ’s obedience, either active or passive, but only those who in their course are actuated and influenced by the spirit and not by the flesh. That the righteousness of the law might be fulfilled in us, who walk not after the flesh but after the Spirit.