But it ought to be remembered, as I already observed, that the gift of justification is not separated from regeneration [i.e. sanctification], though the two things are distinct. But as it is too well known by experience, that the remains of sin always exist in the righteous, it is necessary that justification should be something very different from reformation to newness of life. This latter God begins in his elect, and carries on during the whole course of life, gradually and sometimes slowly, so that if placed at his judgment-seat they would always deserve sentence of death. He justifies not partially, but freely, so that they can appear in the heavens as if clothed with the purity of Christ. No portion of righteousness could pacify the conscience.
It must be decided that we are pleasing to God, as being without exception righteous in his sight. Hence it follows that the doctrine of justification is perverted and completely overthrown whenever doubt is instilled into the mind, confidence in salvation is shaken, and free and intrepid prayer is retarded; yea, whenever rest and tranquility with spiritual joy are not established. Hence Paul argues against objectors, that "if the inheritance be of the law, it is no more of promise," (Galatians 3:18.) that in this way faith would be made vain; for if respect be had to works it fails, the holiest of men in that case finding nothing in which they can confide. This distinction between justification and regeneration [i.e. sanctification] (Osiander confounding the two, calls them a twofold righteousness) is admirably expressed by Paul. Speaking of his real righteousness, or the integrity bestowed upon him, (which Osiander terms his essential righteousness,) he mournfully exclaims, "O wretched man that I am! who shall deliver me from the body of this death?" (Romans 7:24;) but retaking himself to the righteousness which is founded solely on the mercy of God, he breaks forth thus magnificently into the language of triumph: "Who shall lay any thing to the charge of God's elect? It is God that justifieth." "Who shall separate us from the love of Christ? shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword?" (Romans 8:33, 35.)
He clearly declares that the only righteousness for him is that which alone suffices for complete salvation in the presence of God, so that that miserable bondage, the consciousness of which made him a little before lament his lot, derogates not from his confidence, and is no obstacle in his way. This diversity is well known, and indeed is familiar to all the saints who groan under the burden of sin, and yet with victorious assurance rise above all fears. Osiander's objection as to its being inconsistent with the nature of God, falls back upon himself; for though he clothes the saints with a twofold righteousness as with a coat of skins, he is, however, forced to admit, that without forgiveness no man is pleasing to God. If this be so, let him at least admit, that with reference to what is called the proportion of imputation, those are regarded as righteous who are not so in reality. But how far shall the sinner extend this gratuitous acceptance, which is substituted in the room of righteousness? Will it amount to the whole pound, or will it be only an ounce? He will remain in doubt, vibrating to this side and to that, because he will be unable to assume to himself as much righteousness as will be necessary to give confidence.
It is well that he who would prescribe a law to God is not the judge in this cause. But this saying will ever stand true, "That thou mightest be justified when thou speakest, and be clear when thou judges," (Psalm 51:4.) What arrogance to condemn the Supreme Judge when he acquits freely, and try to prevent the response from taking affect: "I will have mercy on whom I will have mercy." And yet the intercession of Moses, which God calmed by this answer, was not for pardon to some individual, but to all alike, by wiping away the guilt to which all were liable. And we, indeed, say, that the lost are justified before God by the burial of their sins; for (as he hates sin) he can only love those whom he justifies. But herein is the wondrous method of justification, that, clothed with the righteousness of Christ, they dread not the judgment of which they are worthy, and while they justly condemn themselves, are yet deemed righteous out of themselves. [emphasis and bracket comments added]Calvin, John. Institutes: Christian Religion 3.11.11