The words righteous or righteousness in English translations of the Scriptures describe primarily personal character as demonstrated in appropriate behavior. But justify, justified and justification have a slightly different focus.
Scholars, while correctly defining justification as meaning "to impute righteousness" or "to be declared righteous," may draw wrong conclusions from these definitions. Though not technically inaccurate, using the English words righteous and righteousness in defining or describing justification sometimes obscures important contextual and behavioral distinctions between how Paul in particular uses the words righteousness and justification.
In Paul's letters the focus of justification is mostly on the legal acquittal of guilt, while righteousness is used mostly in reference to virtuous character. Justification—being legally declared free from guilt—does not instantly make one perfectly righteous. Paul makes it very clear that growth in godly righteousness is a process.
That process starts with baptism, "For as many of you as were baptized into Messiah have put on Messiah" (Galatians 3:27). But attaining the mature righteousness of Yeshua Messiah is a goal toward which we must continue to strive. It is not bequeathed to us instantaneously but comes through a spiritual growth process as we learn from the Scriptures through the guidance of others who have preceded us in Messiah.
"And He Himself gave some to be apostles, some prophets, some evangelists, and some pastors and teachers, for the equipping of the saints for the work of ministry, for the edifying of the body of Messiah, till we all come to the unity of the faith and of the knowledge of the Son of Elohim, to a perfect man, to the measure of the stature of the fullness of Messiah; that we should no longer be children, tossed to and fro and carried about with every wind of doctrine, by the trickery of men, in the cunning craftiness of deceitful plotting, but, speaking the truth in love, may grow up in all things into Him who is the head—Messiah" (Ephesians 4:11-15).
To remain justified after being forgiven, one must behave in a righteous or just manner from that time forward. In other words, the faith required to be justified must be confirmed in one's actions. As James explains: "Was not Abraham our father justified by works when he offered Isaac his son on the altar? Do you see that faith was working together with his works, and by works faith was made perfect? And the Scripture was fulfilled which says, 'Abraham believed Elohim, and it was accounted to him for righteousness.' And he was called the friend of Elohim. You see then that a man is justified [made just] by works, and not by faith only" (James 2:21-24).
However, James' words do not in any way imply that forgiveness of sin is earned by one's works. He is only confirming that, once forgiven, continuing in righteous living is necessary. The power and ability to do this comes from Elohim. Notice how Paul explains this: "Therefore, my beloved, as you have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling; for it is Elohim who [actively] works in you both to will and to do for His good pleasure" (Philippians 2:12-13).
Hastings' Dictionary of the Bible gives this distinction in the words justification and righteousness: "Neither the Heb[rew] nor the Greek original allows of any other definition of 'justify' than 'count just'; it is a term of ethical relationship, not ethical quality, and signifies the footing on which one is set towards another, not the character imparted to one" (1996, "Justification, Justify," emphasis added). In other words, once forgiven, one's status in Elohim's eyes is that of a "just" or "righteous" person. The empowerment of Elohim's Spirit enables one to continue in righteousness.
But much character building still lies ahead. A justified person is not to take his righteousness for granted. It must be increased according to the example of righteousness set by Yeshua Messiah. Each child of Elohim is expected to learn and grow toward "the measure of the stature of the fullness of Messiah."