Our faith in Christ does not free us from works but from false opinions concerning works,

Our faith in Christ does not free us from works but from false opinions concerning works, that is, from the foolish presumption that justification is acquired by works. Faith redeems, corrects, and preserves our consciences so that we know that righteousness does not consist in works, although works neither can nor ought to be wanting; just as we cannot be without food and drink and all the works of this mortal body, yet our righteousness is not in them, but in faith; and yet those works of the body are not to be despised or neglected on that account. In this world we are bound by the needs of our bodily life, but we are not righteous because of them. "My kingship is not of this world" [John 18:36], says Christ. He does not, however, say, "My kingship is not here, that is, in this world." And Paul says, "Though we live in the world we are not carrying on a worldly war" [II Cor. 10:3], and in Gal. 2[:20], "The life I now live in the flesh I live by faith in the Son of God." Thus what we do, live, and are in works and ceremonies, we do because of the necessities of this life and of the effort to rule our body. Nevertheless we are righteous, not in these, but in the faith of the Son of God.

- Martin Luther

Treatise on Christian Liberty