“It is of the utmost importance that we highly esteem, honor, and rely upon the holy sacraments, which contain nothing but God’s words, promises, and signs. This means that we have no doubts about the sacraments or the things of which they are certain signs, for if we doubt these we lose everything. Christ says that it will happen to us as we believe. What will it profit you to assume and to believe that sin, death, and hell are overcome in Christ for others, but not to believe that your sin, your death, and your hell are also vanquished and wiped out and that you are thus redeemed? Under those circumstances the sacraments will be completely fruitless, since you do not believe the things which are indicated, given, and promised there to you. That is the vilest sin that can be committed, for God himself is looked upon as a liar in his Word, signs, and works, as one who speaks, shows, and promises something which he neither means nor intends to keep. Therefore we dare not trifle with the sacraments. Faith must be present for a firm reliance and cheerful venturing on such signs and promises of God. What sort of a God or Savior would he be who could not or would not save us from sin, death, and hell? Whatever the true God promises and effects must be something big.”

- Martin Luther, "A Sermon on Preparing to Die," pp. 109-10 in vol. 42 of Luther's Works, American Edition, edited by Martin O. Dietrich