But no one has abused this book more wickedly than those schools of theologians who have twisted the passage (9:1) “Man does not know whether he deserves love or hate” to apply to the conscience in relation to God. They have twisted it in such a way that they utterly destroyed the consciences of all with their torture. They completely extinguished the certainty of faith in Christ and all knowledge of Christ, teaching and inculcating nothing more religious upon suffering hearts than to tell them that they must be in doubt and uncertainty about the grace and love of God toward us, regardless of how blameless our lives may be. So dense was the darkness, worse than that of Egypt, that this statement of Solomon—or, rather, their own errors, smuggled into this statement—prevented them from seeing any longer the writings of the apostles and evangelists, which declare with such great signs, texts, and arguments that Christ is our Mediator and is the Author of an absolutely certain grace and salvation, freely offered to us and conferred upon us by God.
Luther’s works, vol. 15:
Notes on Ecclesiastes, Lectures on the Song of Solomon and Treatise on the Last Words of David
Preface of Doctor Martin Luther
To His Lectures on the Ecclesiastes
Of Solomon, Delivered
In the School at Wittenberg