The Luther Seal (or Luther Rose) is a widely recognized symbol for Lutherans. It was the seal that was designed for Martin Luther in 1530 at the command of the Elector John Frederick of Saxony, Head of the Protestant Confederation of Germany and "Champion of the Reformation." The seal was designed while Luther was staying at the Coburg Fortress in Bavaria during the General Aassembly of the Holy Roman Empire being held in the Augsburg, Germany (Diet of Augsburg). It was at this meeting of notable clergy, nobility, and commoners that the Protestant Confederation of Germany presented the Augsburg Confession, the primary confession of faith of the Lutheran Church and one of the most important documents of the Protestant Reformation. The prince had personally visited Luther in the Coburg fortress and presented him with a signet ring displaying the seal. Luther used the new seal to authorize his correspondence.

Here is Luther’s interpretation of his seal:

“Grace and peace from the Lord. As you desire to know whether my painted seal, which you sent to me, has hit the mark, I shall answer most amiably and tell you my original thoughts and reason about why my seal is a symbol of my theology. The first should be a black cross in a heart, which retains its natural color, so that I myself would be reminded that faith in the Crucified saves us. "For one who believes from the heart will be justified" (Romans 10:10). Although it is indeed a black cross, which mortifies and which should also cause pain, it leaves the heart in its natural color. It does not corrupt nature, that is, it does not kill but keeps alive. "The just shall live by faith" (Romans 1:17) but by faith in the crucified. Such a heart should stand in the middle of a white rose, to show that faith gives joy, comfort, and peace. In other words, it places the believer into a white, joyous rose, for this faith does not give peace and joy like the world gives (John 14:27). That is why the rose should be white and not red, for white is the color of the spirits and the angels (cf. Matthew 28:3John 20:12). Such a rose should stand in a sky-blue field, symbolizing that such joy in spirit and faith is a beginning of the heavenly future joy, which begins already, but is grasped in hope, not yet revealed. And around this field is a golden ring, symbolizing that such blessedness in Heaven lasts forever and has no end. Such blessedness is exquisite, beyond all joy and goods, just as gold is the most valuable, most precious and best metal. This is my [summary of theology]. I have wanted to show it to you in good friendship, hoping for your appreciation. May Christ, our beloved Lord, be with your spirit until the life hereafter. Amen.”

(Luther, Martin. Luther's Works, v. 49, 356-359, © St. Louis: Concordia Publishing House; Minneapolis: Fortress Press, 1957-1986).
For by grace you have been saved through faith. is the gift of God, not a result of works, so that no one may boast. ~ Ephesians 2:8, 9