Blog 207: 4.14.4 - 4.14.8
Following on his dictum that word and sign belong together, Calvin insists, "The sacrament requires preaching to begat faith." Far from the Romanist understanding that the mere "mumbling" of the word-based formula, "without meaning and without faith," was required, Calvin insisted that the faith in the preached Word, filled with meaning and begetting faith, caused the sacrament to function as a true sign pointing to Christ (4.14.4).
Not only are sacraments signs, they also serve as seals. This image of "seal" refers to a government document or other public act "that is nothing taken by themselves," but with the seal serve to draw our faith to the promise in the public act. And so, the sacraments serve to confirm and assure our hearts that the promise that God holds out in the sacraments is true, trustworthy, and directed for us (4.14.5)
But there is a third image that Calvin uses to talk about the sacraments: a mirror. Now "mirror" language is important for Calvin--creation serves as a mirror to see God's glory (1.5.1); the Word serves as a mirror (3.2.6, 29). Here Calvin says, "We might call them [the sacraments] mirrors in which we may contemplate the riches of God's grace, which he lavishes upon us. For by them he manifests himself to us...as far as our dullness is given to perceive, and attests his good will and love toward us more expressly than by word" (4.14.6).
And yet, the sacraments only serve as signs, seals, and mirrors to those who receive them by faith: "it is therefore certain that the Lord offers us mercy and the pledge of his grace both in his Sacred Word and in his sacraments. But it is understood only by those who take word and sacraments with sure faith, just as Christ is offered and held forth by the Father to all unto salvation, yet not all acknowledge and receive him" (4.14.7).
Whether in baptism or supper, only those who receive the promise held out by faith will receive the benefit promised. In other words, it is not the bare reception of the sacrament, but faith that enables one to receive it as a sign, seal, and mirror of God's grace in Jesus Christ.