Found on Pastor Matt Richard’s blog, PM notes:
Therefore, as I often warn you, doctrine must be carefully distinguished from life. Doctrine is heaven; life is earth. In life there is sin, error, uncleanness, and misery… Here love should condone, tolerate, be deceived, trust, hope, and endure all things (1 Corinthians 13:7); here the forgiveness of sins should have complete sway, provided that sin and error are not defended. But just as there is no error in doctrine, so there is no need for any forgiveness of sins. Therefore, there is no comparison at all between doctrine and life. “One dot” of doctrine is worth more than “heaven and earth” (Matt. 5:18); therefore we do not permit the slightest offense against it. But we can be lenient toward errors of life. For we, too, err daily in our life and conduct; so do all the saints, as they earnestly confess in the Lord’s Prayer and the creed. But by the grace of God our doctrine is pure; we have all the articles of faith solidly established in Sacred Scripture.
-Martin Luther LW: 27:41-42