The English word righteous was coined by William Tyndale, who remodelled the word after an earlier word rihtwis, which would have yielded Modern English *rightwise or *rightways. He used it to translate the Hebrew root צדקים (TzDYQ), tzedek, which appears more than five hundred times in the Hebrew Bible, and the Greek word δικαιος (dikaios), which appears more than two hundred times in the New Testament.
Righteousness is one of the chief attributes of God. Its chief meaning concerns ethical conduct. (E.g., Leviticus 19:36; Deuteronomy 25:1; Psalm 1:6; Proverbs 8:20) It is used in a legal sense; while the guilty are judged, the guiltless are deemed righteous. God's faithfulness to His covenant is also a large part of His righteousness. (Nehemiah 9:7-8)
Righteousness also relates to God's role as saviour; God is a "righteous saviour"; (Isaiah 61) and a deliverer. (Isaiah 46:12-13) The righteous are those who trust that they will be vindicated by the Lord God. (Psalm 37:12-13).
In the Book of Job the title character is introduced to us as a person who is "perfect" in righteousness. This does not mean that he is sinless."Perfect" in this sense means that his righteousness permeates every relationship of his life as his working principle. After all, righteousness is a matter of relationships - with God, with things, and with other people. The biblical definition of righteousness involves the inherent quality of God. God is right because He is righteous, therefore God can only act righteously. In one instance the word means being right; in another it is used to mean doing right; in still another case it means putting right. Job qualifies as a righteous person on each of these counts, so much so that he is commended by God as "wholly righteous" or, translated into our terms, "perfect."
Righteousness as it is understood in the Old Testament is a thoroughly Hebraic concept at variance with the common understanding of the term. The failure to comprehend its meaning is perhaps the most responsible for the view of the Old Testament religion as legalistic and as far removed from the graciousness of the New Testament. See also supersessionism and Christian-Jewish reconciliation.
The New Testament continues the Hebrew Bible's tradition of the ethical and legal aspects of righteousness, but adds the element that Jesus embodies righteousness, (). According to the New Testament, Jesus came to the world to address the needs, not of "the righteous", but of "sinners," (). Righteousness, like the Kingdom of Heaven, is God's gift through grace, ().
Paul of Tarsus speaks of two ways, at least in theory, see also dual-covenant theology, to achieve righteousness: through the Torah, the law of Moses; and through faith in the atonement made possible through the death and resurrection of Jesus Christ, (). The New Testament speaks of a salvation founded on God's righteousness, as exemplified throughout the history of salvation narrated in the Old Testament, ().
The apostle James speaks of the relationship between works of righteousness and faith saying that "faith without works is dead." Righteous acts according to James include works of charity as well as avoiding sins against the law of Moses (). Righteousness means "right doing".