The Bible clearly teaches that we cannot be saved by good works. And the Bible also clearly teaches we cannot be saved without good works. This is a notorious “contradiction,” but it is only an apparent one. The tension is usually resolved by speaking of works that precede salvation and works that follow salvation. In other words, we cannot be saved by good deeds done prior to conversion, but we must produce righteous works after conversion as the fruit of salvation.
Another common explanation is that we cannot be saved by the works of the Law of Moses, the sacrifices and services of the Old Covenant Temple; but we shall be judged by the good works we produce after we are baptized into the New Covenant and fulfill the Law of Christ. Both explanations have a certain truth to them, but I think there is something deeper at work here.
It seems to me that Scripture is teaching us that the works by which we are judged are the works of God in Christ through the Spirit in us. Thus, the works that are accepted in God’s sight at the Judgment are the righteous works of Christ in us. Our good works cannot be our good works at all. Our good works must be the good works of Christ in us by the indwelling power of the Holy Spirit. We cannot present our fleshly righteousness for justification before God, whether prior to or after conversion, for the works of man are done in the power of man to the glory of man. However, the works of Christ within us are done by the power of God to the glory of God.
And of course, in a sense, this carries further both points of view mentioned above. The works of Christ in us certainly are the righteous works that follow conversion and are the works that accompany New Covenant salvation. The work of Christ in us is neither our own pre-conversion self-righteousness nor a Judaistic preservation of Old Covenant works.
The key verse is in Philippians 1 where we are told to “work out our own salvation with fear and trembling; for it is God that works in us.” Here lies the answer to the problem. We work out our own salvation as God works in us. It is not so much a matter of timing, before or after conversion. Neither is it merely a matter of Old and New Covenant. It is a matter of works done by man to the glory of man vs. works done by God to the glory of God.
Are our good works flowing out of human strength? Then, those works cannot save us no matter when they are done. Are our works flowing out the power of the Holy Spirit? Then we shall be judged by those works—the works of Christ in us—and we shall be saved by those works. As Paul says elsewhere, the works of man shall be burned up whereas the works of the Spirit shall endure (I Co 3).
The bottom line? Our righteous works must be done through the power of the Holy Spirit. Fleshly works cannot save the sinner or the saint. We all must be filled with the Spirit and confess that the works we do, we do by the power of God.