From God’s Strategy In Human History by Roger T. Forster and Paul Marston:
The words “justify” and “righteous” are from the same Greek root.
To quote Dr. Leon Morris on the word justify, “When we turn to these passages where the verb ‘to justify’ occurs, there can be no doubt that the meaning is to declare righteous rather than to make righteous.”
Morris states that the modern western conception of the word righteous is not at all what the biblical term means. Today we think a righteous person is someone who lives up to a code of conduct; a perfectly righteous man would be one who lived according to some moral law. This understanding of the term righteous makes it an ethical term. This understanding is similar to the Greek understanding of the term. But this is not the Hebrew understanding of the term. To quote Morris, “The Hebrew concept is not grasped by making a facile equation with the Greek…or the English ‘righteousness’, it is not an ethical term but a religious.” Why is the term religious? To the Hebrews the term righteous meant primarily that a man was right with God and only secondarily that he would act in a manner befitting this position. The righteous are those acquitted at God’s bar of justice and righteousness is the standing of those who have been acquitted. This concept of a great assize was developed and elaborated by the rabbis. All men would be tried by God; some would be accepted as righteous, others condemned as wicked. It was from this mindset that the New Testament terminology concerning righteous and righteousness was derived. The righteous man is one who is accepted by God , the one who conforms to His way. To the Hebrew, being righteous meant, by primary definition, being right with God and ethical behavior was the expected result and reflection of this.
God’s righteousness: (How can God be righteous if righteous means to be right with God? The word means slightly more than this. It is used five times as an adjective referring to God) Jn. 17:25(General reference), Rom 3:26, 2Tim 4:8, 1Jn. 1:9 (God’s forgivness is in accordance with the laws of His holy nature) , Rev. 16:5 (Here the Lord is shown to be righteous by the process of just judgement, which is in accordance to the meaning in 2Tim. 4:8).
Job and Righteousness: In view of the Hebrew concept of the term righteous, Job was righteous before God in that he was in right standing before God. (The same could be said of Lot and Noah.) Job’s claim was to be in a fundamentally right standing with God, and because of the Hebrew concept of the term, God condoned what he said. See Job 13: 18, 40:8. It is this background that gives understanding to the questions asked in Job 9:2, 15:14, 25:4. In each case it is one’s standing with the Lord that is in question and the implication is that one cannot earn that standing in his own strength. To quote Morris, “The Bible does not necessarily condemn the claim of a man to be righteous. What is wrong is a claim to be able to make oneself righteous, i.e., to earn God’s acquittal.”
Gentiles, Jews, and Righteousness: The Hebrew understanding of the term righteous must be applied to verses such as Rom. 9: 30-32. If we applied the ethical understanding of the term, the verse would seem to say, “The Jews were trying very hard to lead moral lives but the Gentiles were not. Then the Gentiles found themselves acting morally and Jews could not.” This is certainly not the intended meaning. Paul was referring to the Jews attempt to achieve right standing with God through their intense quest to keep the whole of the Law. Its not that the Gentiles had no interest in being right with God, but their interest was small in light of the obsession of the Jews to keep the Law. The Gentiles were acquitted, had right standing with God through faith, not the works of the Law.