Christian Liberty where the commands of God do not clearly communicate

"Already, at an early date, we have taught Christian liberty from [the writings] of St. Paul. There is to be freedom of choice in everything that God has not clearly taught in the New Testament, for example, in matters pertaining to various foods, beverages, attire, places, persons and various forms of conduct [Rom. 14:2-6; 1 Cor. 8:8-10]. We are obligated to do nothing at all for God, except believe and love. Now tell me, where has Christ forbidden us to elevate the sacrament or commanded us to elevate it? Show me one little word, and I will yield. Yet Dr. Karlstadt ventures to burst out and say that it is forbidden by Christ, and considers it a sin as great as the denial of God. He is unable to prove this. Nor is it true. Is it not a woeful, pitiable blindness, so to burden souls with sin and murder them, and make laws where none exist?" -Martin Luther, Against the Heavenly Prophets, Pg. 205-206