The heart of a covenantal understanding of the Lord’s Supper is that through the sacrament, God established, sustains, and exercises the covenantal relationships between God and His people. These are the relationships of mercy and love, faith and faithfulness, paternal care and thankfulness. The Lord’s Supper eloquently reveals God as Father, who nourishes at His table the very children He received into His household by baptism. Consider the words of Calvin
God has received us, once for all, into his family, to hold us not only as servants but as sons. Thereafter, to fulfill the duties of a most excellent Father concerned for His offspring, He undertakes also to nourish us throughout the course of our life. And not content with this alone, He has willed, by giving His pledge, to assure of this continuing liberality. To this end, therefore, he has, through the hand of his only-begotten Son, given to His church another sacrament, that is, a spiritual banquet, wherein Christ attest himself to be the life-giving bread, upon which our souls feed unto true and blessed immortality. The Institute of Christian Religion IV, xvii
The key words here are “by giving His pledge.” The Lord’s Supper gives us God’s oath, that is, His promise to bring us through the trials of this life well supplied by his grace until at last we enter His eternal presence. In effect, the Lord’s Supper is our heavenly manna which sustains us as we journey through the wilderness to our glorious inheritance. This spiritual banquet attests that Christ is indeed our Savior. When the God who has granted us the covenant is revealed to be our Father, then we are revealed to be the children of God. With paternal love and generosity, God the Father nourishes His beloved sons and daughters to eternal life.
When we sit at His table, we discover God to be our Father and we exercise our relation to the Father. We experience His paternal love as well as the fraternal love of fellow Christians. For this reason, the Lord’s Supper is a profound experience, in which the eternal realities of God’s kingdom deeply affect us. In this sense, the Lord’s Supper is the place where the richness of God’s grace is manifested and the wonder of God’s adoptive love is put upon display (cf. 1 John 3:1).
The relationships of the New Covenant were established by the sacrifice of Christ and are both redemptive and eternal. Our union with Christ is, by nature, mysterious and incomprehensible, but by giving guarantees through the Lord’s Supper, our Father makes this union as certain for us as if we had seen it with our own eyes. The broken bread and spilled wine assure us that the broken body and poured out blood of Christ nourish us to eternal life. They nourish us in the covenant relationship we have with our Savior, who has established the New Covenant as the eternal covenant. To this end, the words of promise are added to the Lord’s Supper: “Take, this is my body which is given for you” (cf. Luke 22:19). In commenting about this passage, Calvin writes
We are called to take and eat the body which was once for all offered for our salvation in order that when we see ourselves made partakers in it, we may assuredly conclude that the power of His life-giving death will be efficacious in us. The Institute of Christian Religion IV, xvii
It is the same way with the words of promise which accompany the cup: “This cup is the new covenant in my blood” (cf. Luke 22:20). With these words, says Calvin, Christ “renews, or rather continues, the covenant which he once for all ratified with His blood… whenever he proffers that sacred blood for us to taste.”
Finally, the Lord’s Supper reveals an aspect of the New Covenant which had only been foreshadowed in the Old Covenant. In the Old Covenant, the promise is: I shall be your God and you shall by My people. However, in the New Covenant, the promise becomes much more profound and personal: I shall be your Father and you shall be my children. May we consider these eternal realities as we receive communion on this Lord’s Day.