In Christ, the old man governed by fleshly desires is crucified (Romans 6:6).

The law, once weakened by the flesh (Romans 8:3), could not produce righteousness. But in Christ, the Spirit takes over, fulfilling the righteous requirements of the law in us who walk not after the flesh but after the Spirit (Romans 8:4).

Thus, the believer is no longer under the tyranny of flesh but under grace, empowered by the Spirit to live perpetually in Christ.