12. Although, with regard to the office a calling is required in order to administer a sacrament in the correct manner, we do not therefore judge that the sanctity of the person is a requirement. Because the minister is acting in this administration on behalf of God and not of himself, we state that the ministers’ dignity, or lack thereof, can neither add nor take away anything at all from the integrity or efficacy of the sacraments. In the same manner those men “who preached Christ out of selfish ambition and not out of good will” (Phil 1:17) detracted nothing from the dignity of God’s Word. In this matter we do not disapprove Thomas’s statement, “The instrument does not work by its own form, but by the strength of him who makes it move” (Summa theologiae 3, question 64, article 5).

Disputation 43, “On the Sacraments in General,” in Synopsis of a Purer Theology, 550-551.