This is an excerpt taken from the preface of Martin Luther’s commentary on Galatians. He writes:

St. Paul sets about establishing the doctrine of faith, grace, forgiveness of sins, or Christian righteousness. His purpose is that we may understand exactly the nature of Christian righteousness and its difference from all other kinds of righteousness, for there are various sorts of righteousness. There is a political or civil righteousness, which emperors, princes of the world, philosophers, and lawyers deal with. There is also a ceremonial righteousness, which human traditions teach. This righteousness may be taught without danger by parents and schoolteachers because they do not attribute to it any power to satisfy for sin, to please God, or to deserve grace; but they teach such ceremonies as are necessary simply for the correction of manners and certain observations concerning this life. Besides these, there is another righteousness, called the righteousness of the law or of the Ten Commandments, which Moses teaches. We too teach this, according to the doctrine of faith.

There is yet another righteousness that is above all these—namely, the righteousness of faith, or Christian righteousness, which we must carefully distinguish from the other sorts mentioned above, for they are quite contrary to this righteousness, both because they flow out of the laws of rulers, the traditions of the church, and the commands of God, and also because they consist in our works and may be performed by us either by our natural strength or else by God’s gift. For these kinds of righteousness are also from God’s gift, just as are other good things that we enjoy.

But this most excellent righteousness—that of faith, I mean—which God imputes to us through Christ, without works—is neither political nor ceremonial, nor is it the righteousness of God’s law, nor does it consist in works. It is quite the opposite; that is to say, it is passive, whereas the others are active. We do nothing in this matter; we give nothing to God but simply receive and allow someone else to work in us—that is, God. Therefore, it seems to me that this righteousness of faith, or Christian righteousness, can well be called passive righteousness.

This is a righteousness hidden in a mystery that the world does not know. Even Christians themselves do not thoroughly understand it and can hardly grasp it in their temptations. Therefore, it must be diligently taught and continually practiced. And whoever does not understand this righteousness when afflicted and frightened in conscience must be overthrown, for nothing comforts our conscience so firmly and securely as this passive righteousness.