“In the church nothing other than the gospel shall be preached. … See there what the gospel is: a joyous sermon concerning Christ, our Savior. He who preaches him properly, preaches the gospel and nothing but joy. What greater joy may a heart know than that Christ is given him as his very own? … If there were something else to preach, then the evangelical angel and angelic evangelist would have touched on it.”

Martin Luther. ‘The Gospel for Christmas Eve’ from the Christmas Postil. Luther’s Works, American Edition, vol. 52. (Philadelphia: Fortress Press, 1974), p. 18, 20-21.