Every once in a while, you will encounter a person trying to tell you that Lutherans teach that people MERELY are imputed righteous and that God forgives their sin but leaves them still in it. This ALWAYS gets my dander up, because our Symbols are very clear in expressing our teaching on this point, and that is NOT it. Rather, we teach the following:
Ap IV:78 We understand justification as the making of a righteous person out of an unrighteous one, or that a person is regenerated.
Ap IV:115 115 Nor, indeed, is this faith an idle knowledge, neither can it coexist with mortal sin.
Ap IV: 142 Likewise, the faith of which we speak exists in repentance. I mean that faith is conceived in the terrors of conscience, which feels God’s wrath against our sins and seeks forgiveness of sins, seeks to be freed from sin. In such terrors and other troubles, this faith ought to grow and be strengthened. 143 Therefore, it cannot exist in people who live by the flesh, who are delighted by their own lusts and obey them.
SA III:iii:40 In Christians, this repentance continues until death. For through one’s entire life, repentance contends with the sin remaining in the flesh. Paul testifies that he wars with the law in his members (Romans 7:14–25) not by his own powers, but by the gift of the Holy Spirit that follows the forgiveness of sins [Romans 8:1–17]. This gift daily cleanses and sweeps out the remaining sins and works to make a person truly pure and holy.
SA III:iii:44 The Holy Spirit does not permit sin to have dominion, to gain the upper hand so it can be carried out, but represses and restrains it from doing what it wants [Psalm 51:11; Romans 6:14]. If sin does what it wants, the Holy Spirit and faith are not present. 45 For St. John says, “No one born of God makes a practice of sinning … and he cannot keep on sinning” [1 John 3:9]. And yet it is also true when St. John says, “If we say we have no sin, we deceive ourselves, and the truth is not in us” [1:8].
FC SD 1:14 Fifth, this hereditary evil is so great and horrible that, only for the sake of the Lord Christ, can it be covered and forgiven before God in those baptized and believing. Furthermore, human nature, which is perverted and corrupted by original sin, must and can be healed only by the regeneration and renewal of the Holy Spirit [Titus 3:5]. However, this healing is only begun in this life. It will not be perfect until the life to come [Ephesians 4:12–13].
FC SD 1:39 Here pious Christian hearts justly ought to consider God’s unspeakable goodness. God does not immediately cast from Himself this corrupt, perverted, sinful material into hellfire. No, He forms and makes the present human nature from it (which is sadly corrupted by sin) in order that He may cleanse it from all sin, sanctify, and save it by His dear Son.
FC SD 1:45 Third, in the article of Sanctification Scripture testifies that God cleanses, washes, and sanctifies mankind from sin [1 Corinthians 6:11; 1 John 1:7] and that Christ saves His people from their sins [Matthew 1:21]. Sin, therefore, cannot be a person himself. For God receives a person into grace for Christ’s sake. But God remains hostile to sin eternally.
FC SD 2:70 This is certainly true: in genuine conversion a change, new emotion, and movement in the intellect, will, and heart must take place. The heart must perceive sin, dread God’s wrath, turn from sin, see and accept the promise of grace in Christ, have good spiritual thoughts, have a Christian purpose and diligence, and fight against the flesh. Where none of these happen or are present, there is no true conversion.
So no more MERE, please. As Dr. Luther never tired of explaining this, there is grace (God's gracious pardon and the imputation of the righteousness of Christ) and the GIFT that is in grace (the Holy Spirit). The two always come together and cannot be separated, though they are always distinguished. Our righteousness before the throne of God will remain always the Divine-Human Person and finished work of the Redeemer and never the incipient righteousness that the Holy Spirit has begun and continues - really and truly - working within us.