Our Lord Jesus instituted two covenantal sacraments for the church: baptism and the Lord’s Supper (also called Communion or the Eucharist). Sacraments are holy ordinances instituted by Christ for His church, which are made up of a signs and seals of the covenant of grace (WCF 27.1).
The word ‘sacrament’ does not appear in Scripture, like other theological terms such as ‘Trinity’ or ‘incarnation’. Classically, the word was used for anything that bound or brought one under an obligation, such as an oath. In church history, the word became the Latin equivalent of the Greek word mysterion (mystery or hidden thing) and was applied to the Christian rites of Baptism and the Lord’s Supper.
There are two parts to the sacraments. First, there is the outward and visible sign: water for baptism and bread and wine for the Lord’s Supper. Second, there is the inward spiritual grace signified by the sign. This would be Christ and all His benefits, such as righteousness (Rom. 4:11), forgiveness of sins (Mk. 1:4), faith and repentance (Mk. 1:4; 16:16), and communion with Christ (Rom. 6:3–4, Col. 2:11–12). When God’s people receive the sacraments in faith, they see the sign and receive the thing signified, namely, God’s grace.
Sacraments are signs given to believers to accompany the Word, in order to be visible reminders and demonstrations of God’s grace toward us. Calvin defined sacraments as “an outward symbol by which the Lord seals in our consciences the promises of His good will toward us, to sustain the weakness of our faith.” The sacraments must always be accompanied by the Word, “for they have no content of their own, but derive their content from the Word of God; they are in fact a visible preaching of the Word.” The sacraments are not magic, but instead the water, bread, and wine are true visible representations of invisible spiritual things which the Word points us to.
There has been much debate in church history, especially during the Reformation, regarding the relationship between the sign and the thing signified in the sacraments. For example, when a man is baptized, is he immediately and automatically regenerated in the water, receiving both the sign and the salvific grace signified? Or, on the opposite side of the debate, is baptism merely an outward sign signifying regeneration and the new birth, but does not actually convey grace to its recipient? The same questions can be asked of the Lord’s Supper where the bread and wine signify our Lord’s body and blood, but in what way is He actually present and do we receive Him? We will get into the details regarding this for each sacrament in future posts, but in general the Reformed have argued that there is a spiritual union between the sign and the thing signified, where “the names and effects of the one are attributed to the other” (WCF 27.2). Therefore, the union is representative, where the sign really does represent the thing signified; and also instrumental, where by God’s sovereign power, the grace signified is truly conveyed through the sign (WCF 27.2).
Find other posts in this series here.
 A.A. Hodge. The Westminster Confession: A Commentary (UK: The Banner of Truth Trust), 327.
 Louis Berkhof, A Summary of Christian Doctrine (London, UK: Banner of Truth Trust), 154.
 John Calvin, Institutes of the Christian Religion (Peabody, MA: Hendrickson Publishers, Inc.), 4.14.1.
 Louis Berkhof, Systematic Theology (Grand Rapids, MI: William B. Eerdmans Publishing Company), 312.