First off let’s lay to rest any false idea that man can establish His own righteousness. Israel tried and failed. Righteousness makes it possible for a man to come into the presence of God.
“For not knowing about God’s righteousness and seeking to establish their own, they did not subject themselves to the righteousness of God.” (Rom. 10:3)
There is in the world the unrighteousness of man who has trespassed against God. “None are righteous, no, not one” (Rom. 3:10). And there is the righteousness of God. It flows from His perfection, was exemplified perfectly through Jesus Christ, and is in every Christian through God’s gift of grace AND by Christians doing the righteousness of God. David said,
”The LORD has rewarded me according to my righteousness; According to the cleanness of my hands He has recompensed me.” (Ps. 18:20).
A man recently told me his salvation had NOTHING to do with what he does. That was interesting to hear because I wondered if he thought he is better than David? David was justified by His faith because, like Abraham, he believed in God and obey Him. What many religious folks fail to discern is that faith in God – not in one’s own deeds – does not preclude or negate the need for deeds. A man doesn’t really trust in God who does not obey God.
I understand though that the man has bought into the “cheap grace” adopted by the so-called Reformers who set out at first to escape the traditions of Catholicism but went too far and established a different error. “Faith only” doctrine as taught today is a contradiction of the Word of God which says “You see that a man is not justified by ‘faith alone'”. “Faith alone” doctrine of Luther and other Reformers does not mean “saved by God’s righteousness, not mine”, but now it means “God saves a person before he repents, before baptism, before he confesses any faith.”
I’m not sure how such a serious error could become so mainstream, but it is dangerous because it encourages do nothing faith. David, the man of faith, said it himself that “God rewards the righteous” and Jesus said, “If you love me, you will keep my commandments.” True faith acts and God rewards.