When people ask me why I preach the righteousness of Christ so much, I answer it is because God must be glorified, Christ must be exalted, all boasting must be excluded in ourselves, and we must be encouraged to persevere and obey with the absolute certainties of God's grace. Nothing else will accomplish all this but the preaching of Christ and His righteousness as the only ground of the whole of salvation. The main issue in salvation is the glory of God. The main issue in the glory of God is the righteousness of Christ by which God is enabled to be both a just God and a Savior. This is God's redemptive glory (Isa. 45:21-22), and this is where Christ is exalted and given the pre-eminence as Lord of all (2 Cor. 4:6).
Whenever we preach or teach any subject from the Bible, this message of grace is the very thing God the Holy Spirit uses to empower the truth for the salvation of sinners and the edification of God's people. Without it, the message simply blends in with the rest of false religion in its moral pep talks and psychological babbling (Matt. 5:13-16). Without this message of grace, Christ and His righteousness as the only ground of salvation, the salt loses its savor and is good for nothing but to be cast out. Think about this seriously. There are many other things in the Bible we need to hear, learn, and practice, but all things in the Bible are to be preached in light of this Gospel (Rom. 1:16-17). Without this, there is no Gospel.