Throughout church history, the sacraments have been the subject of many heated debates because Christians have recognized that baptism and the Lord’s Supper are not empty rites. Instead, they are signs of God’s promise and faithfulness and, as such, “there is a spiritual relationship between the sign and that which it signifies. That relationship is established by God, who himself attaches the significance to the sacrament” (R.C. Sproul, Truths We Confess, vol. 3, p. 87). So, although the spiritual realities depicted in baptism and the Lord’s Supper are not caused by the performance of the sacraments themselves, the benefits signified and sealed in the sacraments are given in the sacraments to those who have true faith because of the promises of God.
First and foremost, the sacraments are signs of God’s faithfulness to His covenant. There is, of course, a sense in which we participate in the sacraments as a testimony to the watching world, but that is not the primary emphasis of baptism and the Lord’s Supper. These sacraments, alongside the preached Word of God, are designed primarily to show forth God’s trustworthiness. His faithfulness does not depend on the faithfulness of those who serve in His name (2 Tim. 2:13), nor does it depend on the strength of our trust in Him (Luke 22:31–34). Our Creator always keeps His promises.
Consequently, God never fails to keep His promise in baptism that He will cleanse from sin all those who trust in Christ alone for salvation. The outward washing in water, as question and answer 72 of the Heidelberg Catechism remind us, does not in itself wash away our transgressions. That is accomplished only if we are washed by faith in the blood of Jesus and in His Spirit (1 John 1:7). Nevertheless, the promise given in baptism is a real promise, and the Lord has bound Himself to keep this promise when those who are baptized outwardly come to faith in Christ Jesus. At that point of conversion, the outward baptism is fulfilled in the spiritual baptism into Christ and His benefits that the Holy Spirit accomplishes (Gal. 3:27).
As with the Word of God preached, a sacrament performed according to the directions of Jesus our Lord will accomplish its purposes. It is a promise of God used to build up His elect, but it is also a promise of judgment on all those who reject the promise signified in the sacrament.
“Just as the Word of God does not return to him void, neither does the exercise and administration of his sacrament return to him void” (R.C. Sproul, Truths We Confess, vol. 3, p. 89). The preaching of God’s Word will either soften hearts and incline them to His truth, or it will harden hearts against His promises. So it is with the sacraments. We must never take these ordinances lightly but examine ourselves before we witness or participate in them.