Paul's lexical anchor

The decisive New Testament text is 1 Corinthians 10:16:

τὸ ποτήριον τῆς εὐλογίας ὃ εὐλογοῦμεν, οὐχὶ κοινωνία ἐστὶν τοῦ αἵματος τοῦ Χριστοῦ; — The cup of blessing that we bless, is it not a participation in the blood of Christ?

τὸ ποτήριον τῆς εὐλογίας — the cup of the blessing. [•] reads this technical phrase as a fixed Jewish meal-blessing idiom that the apostle deploys with no explanation. The cup over which a thanksgiving was pronounced after a meal — the "cup of blessing" — was a known cup in first-century Jewish meal practice, and Paul identifies the Eucharistic cup as that cup. [•] and [•] follow Calvin on the lexical observation; [•] traces the same identification through Mark.

What Paul calls κοινωνία — participation, communion, sharing — is the heart of Reformed sacramental theology. The Reformed tradition stands between two errors:

• Roman-Catholic conflation — that the elements become the body and blood of Christ in their substance, and that the Mass re-presents the sacrifice of the cross. [•] rejects this on christological and biblical grounds; [•] defends the rejection systematically.
• Zwinglian reduction — that the elements are only memorial signs and that no objective grace is given through them. [•] rejects this too. The Reformed cup is not a bare memorial; it is the appointed means by which Christ communicates the benefits of his cross to faith.

Calvin's position — and the position of every Reformed confession that follows him — is that the believer truly partakes of Christ in the Supper, not by a change in the elements but by the working of the Holy Spirit lifting the believer's heart to where Christ now is. [•] calls this the sursum corda movement: lift up your hearts. We have them lifted up unto the Lord.

The Synoptic and Pauline accounts

Element	Mark 14:22–25	Matt 26:26–29	Luke 22:14–20	1 Cor 11:23–26
Bread broken	v. 22	v. 26	v. 19	v. 24
Cup over wine	v. 23	v. 27	vv. 17, 20	v. 25
"After supper" formula	absent	absent	v. 20	v. 25
Covenant language	"blood of the covenant"	"blood of the covenant"	"new covenant in my blood"	"new covenant in my blood"
Vow of abstention	v. 25	v. 29	v. 18	implicit
Hallel sung	v. 26	v. 30	absent	absent

Several patterns emerge. Mark and Matthew present a single cup at the institution; Luke distinctly narrates two cups (vv. 17 and 20), with the explicit μετὰ τὸ δειπνῆσαι attached to the second. Paul's wording in 1 Corinthians 11 reproduces Luke's "after supper" cup verbatim — these two share a tradition. [•] argues persuasively that Paul's source is the Antiochene tradition Luke also drew on; [•] concurs.

The decisive lexical detail is "after supper." A meal punctuated by a cup before the food and a cup after the food matches the post-meal cup of blessing that [•] identifies in 1 Cor 10:16. The post-meal cup is the institution cup — the cup of the new covenant.

"This is my blood of the covenant"

Calvin's exposition of the institution words turns on the word covenant — διαθήκη. [•] reads Jesus's saying through Exodus 24:8, where Moses sprinkles blood on the people and declares, "Behold the blood of the covenant that the LORD has made with you." Jesus, Calvin notes, is doing what Moses did — and more.

Moses took the blood and threw it on the people and said, "Behold the blood of the covenant that the LORD has made with you in accordance with all these words."

This is my blood of the covenant, which is poured out for many.

The substitution is precise. The blood of bulls ratified the Mosaic covenant; the blood of the Mediator ratifies the new. [•] treats the Last Supper cup as the seal of the expiation that the cross will accomplish. The cup is not the sacrifice itself; it is the signum of the sacrifice — the visible, drinkable pledge that the new covenant is sealed in his blood. [•] develops the same point: the believer who drinks in faith truly receives Christ, and what is signified in the sign is given to the soul through the working of the Spirit.

For penal-substitutionary atonement, the cup matters because it ties the supper to Jeremiah 31:31–34:

I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. … For I will forgive their iniquity, and I will remember their sin no more.

That last phrase is forensic. [•] reads it under the doctrine of justification: God remembers our sin no more because the record of debt has been canceled in the blood of his Son (Col 2:14). [•] sets the same point in the context of definite atonement: the Mediator's blood actually secures the forgiveness it announces. [•] takes the new covenant as the fulfillment of the covenant of grace which God has been administering since the protoevangelium.

The Last Supper announces what the Cross will accomplish. [•] writes, "the language of the institution is the language of substitution." That is the cup the Reformed Church holds in her hand on the Lord's Day.

What the Reformed confessions actually say

Six confessional statements shape the Reformed reading of the cup of blessing. They are remarkably unanimous.

Westminster Confession of Faith ch. 29

Note the architecture: remembrance of the sacrifice, sealing of its benefits, nourishment in Christ, engagement in obedience, bond of communion. The cup of blessing does five things in this paragraph. [•] works through each clause; [•] Q. 168–177 expands them.

Heidelberg Catechism Q. 75

The Heidelberg locates the believer's assurance of Christ's atoning work in the receiving and tasting of the cup. The visible action is "as certain as" the invisible substance.

Belgic Confession art. 35

The Belgic introduces the famous Reformed image: faith is "the hand and mouth of our soul." The believer truly receives Christ in the sacrament, but the receiving is by faith and through the Spirit, not by a change in the elements.

Canons of Dort

[•] does not treat the Lord's Supper directly, but its second head — particular redemption — is the indispensable backdrop for the Reformed reading of the cup of blessing. The cup is given only to those for whom Christ died. The cup signifies a definite atonement, secured for the elect, applied through the means of grace.

1689 Second London Baptist Confession ch. 30

[•] ch. 30 substantially reproduces Westminster ch. 29 with adjustments for credo-baptism. The Reformed Baptist tradition holds the same sacramental architecture.

Savoy Declaration

[•] in its ch. 30 likewise tracks Westminster's treatment, with congregationalist polity adjustments. The unanimity of the Reformed confessions on the Lord's Supper is a remarkable historical fact.

Calvin's mature sacramental position

[•] develops the most nuanced sacramental theology in Reformed history. The argument is structured around five claims:

1. The signs are not bare signs. Against Zwingli's reduction, Calvin insists that the bread and cup truly convey what they signify. (4.17.10–11)

2. The signs are not transformed. Against Rome's transubstantiation, Calvin argues that Christ's body remains in heaven, glorified and unchanged. The bread is bread; the wine is wine. (4.17.12–18)

3. The believer truly partakes. The mode is real, not merely figurative. Christ feeds the soul with his crucified body and shed blood. (4.17.5–9)

4. The mode is the working of the Spirit. What unites the believer to the heavenly Christ is the Holy Spirit, who lifts the heart to where Christ now is. (4.17.10, 31)

5. The orientation is upward. Sursum corda — "lift up your hearts." The Christian does not bring Christ down to the elements; the Christian is lifted up to Christ. (4.17.31)

[•] calls this Calvin's "true spiritual presence" view, distinct from both consubstantiation and memorialism. [•] argues it remains the strongest Reformed position. [•] reads it as deeply pastoral: the Lord's Supper is a means of grace by which weak faith is strengthened with the body and blood of Christ.

Owen on communion with Christ at the table

[•] develops Reformed sacramental theology in trinitarian devotional terms. The believer at the table communes with the Father (who has accepted the Son's sacrifice), with the Son (whose body and blood are signified), and with the Spirit (who applies the benefits). The Lord's Supper is therefore not just christological — it is a trinitarian event.

[•] goes further: the meditative gaze of the believer on the cup of blessing is the seedbed of every other Christian virtue. The cup is the Reformed believer's most concentrated pastoral resource.

The vow of reservation

The Synoptic record gives us not only the cup of blessing but a parallel act: a cup Christ vows not to drink.

Truly, I say to you, I will not drink again of the fruit of the vine until that day when I drink it new in the kingdom of God.

For I tell you that from now on I will not drink of the fruit of the vine until the kingdom of God comes.

This is the Cup of Reservation — the third of our four cups. [•] reads the vow as the inaugurated-eschatology hinge of the gospel: there is a cup Christ has drunk (the cup of blessing, sealed in his blood at the cross), and there is a cup he has not yet drunk (the cup of consummation at the marriage supper of the Lamb). The believer who eats and drinks at the Lord's Supper inaugurates the kingdom-banquet without yet consummating it.

[•] places the vow inside Reformed eschatology: the Supper is a "memorial-anticipation," looking back to a finished cross and forward to a kingdom not yet fully come. [•] systematizes the same insight through covenant theology.

The Reformed believer therefore drinks the cup of blessing in this register: I am eating with Christ now, and I will eat with Christ then.

The pastoral consequence

Three pastoral applications follow from the Reformed reading of the cup of blessing.

For the believer in dryness. The cup is not a bare memorial. It is the appointed sign and seal of the present Christ, given to weak faith for the strengthening of weak faith. [•] writes that the Reformed sacramental tradition is uniquely pastoral on this point: when the soul cannot generate fresh affection for Christ, the soul can come to the table where Christ presents himself for the soul.

For the believer in conflict. Paul's argument in 1 Corinthians 10–11 turns on the cup as a participation. To eat and drink in faith is to be drawn into a body that does not permit its members to despise one another. The cup of blessing has ecclesiological consequences. If you are estranged from another believer, do not approach the cup without seeking peace (Matt 5:23–24). [•] ties communion with Christ to communion with the saints.

For the unbeliever. The cup is not yours yet. [•] ch. 29.8 says plainly that "all ignorant and ungodly persons, as they are unfit to enjoy communion with him, so are they unworthy of the Lord's table." The Reformed-confessional tradition does not pretend that the Supper is a generic spiritual meal. It is the meal of the new covenant, and one enters the new covenant only through repentance and faith in the Mediator whose blood is signified there.

Continue to Chapter 3 — The cup of wrath for the case that what Jesus prayed about in Gethsemane was the cup the prophets had been pouring for centuries — and why his "let this cup pass from me" is the most theologically dense prayer in the Bible. Calvin, Owen, Edwards, Macleod.