Blog 209: 4.14.14 - 4.14.20
While the sacraments are wonderful gifts given to us by God, we have to say that they are not required for salvation. Nor are they even required for assurance of salvation: "Assurance of salvation does not depend upon participation in the sacrament, as if justification consisted in it. For we know that justification is lodged in Christ alone, and that is communicated to us no less by the preaching of the Gospel than by the seal of the sacrament, and without the latter can stand unimpaired" (4.14.14).
The sacraments only have significance as they point us to Christ. "Christ is the matter," Calvin says, "or (if you prefer) the substance of all the sacraments; for in him they have all their firmness, and they do not promise anything part from him." We are only helped by the sacraments if they "foster, confirm, and increase the true knowledge of Christ in ourselves...to possess him more fully and enjoy his riches" (4.14.16). This knowledge of Christ as we receive the sacraments by faith in God's promises (4.14.17).
However, the sacraments also serve as covenantal pledges. There is a sense in which the mutuality of the covenant is affirmed in baptism and Supper; these signs serve as "marks of profession, by which we openly swear allegiance to God, binding ourselves in fealty to him." Or as Calvin puts it a bit later, "God leagues himself with us and we pledge ourselves to purity and holiness of life, since there is interposed here a mutual agreement between God and ourselves" (4.14.19).