"Christians are people who have been declared righteous by God, who know that justification is by faith only, and that God 'justifieth the ungodly' (Romans 4:5). They believe all Paul's arguments in the first five chapters of Romans. This is how Christians think of righteousness; not little details here and there but this whole matter of their standing before God and the declaration of God that He "accounts" them as righteous.
Not only that, Christians believe that they have been clothed with the righteousness of Jesus Christ, that God has put this "robe of righteousness upon them" (Isaiah 61:10). They know they have been born again, 'born of the Spirit'. They now belong to the realm of righteousness, whereas before they did not.
Here is a man who has a conception of righteousness; he wants to be rid of everything that is wrong; he wants to be wholly right, he is interested in holiness.
Do you see the point? The righteous are unconcious of their righteousness. That is the glory of their whole position. I trust I am making this clear to you. Christians are righteous in themselves because they have been brought into the kingdom of God and the realm of righteousness".
Dr Martyn Lloyd-Jones - "Romans: Exposition of Chapter 14:1-17 - Liberty and Conscience" - Banner of Truth, Edinburgh (2007) - (pp257-265).