"The schisms and heresies against which Paul had to fight in the Church of Corinth seem to have become noticeable first in the celebration of the Lord's Supper... Thus the controversies over the Lord's Supper, which have so often provoked the criticism of Christians and non-Christians - Holy Communion having become the cause of unholy disunion - go back to the time of the New Testament. The reason for such controversies may be found in a lack of love, as seems to have been the case at Corinth. But it may be found also in the fact that every dissension concerning the Gospel necessarily expresses itself in a dissension over the Lord's Supper. Just as the Church of Christ becomes conscious of its own nature as it gathers around the Lord's Table, so its weaknesses, errors, and sins also become manifest on that occasion. Each misunderstanding of the Gospel must lead to a misunderstanding of the Sacrament. Each misunderstanding of the Sacrament is bound to lead to a wrong concept of the Gospel."In other words, the Lord's Supper is not simply one element of Christianity among many, unrelated to other matters like soteriology, Christology, ecclesiology, etc. Since it serves as the center of Christian piety and worship, a person's understanding of the Lord's Supper will inform their thinking on all other matters of faith, and visa verse. Thus, Sasse's words should serve as a warning to all those who would sweep aside differences regarding the Sacraments in the name of ecumenical progress. Disagreement with regards to the Lord's Supper is a sign of major disagreements elsewhere. In Here We Stand, Sasse illustrates this point by referring to the Lutheran/Reformed split that occurred in the 16th century:
Here we see how Luther could not abandon his belief in the Real Presence without destroying his whole understanding of the Gospel in the process.In the 16th century it was the question of the Lord's Supper which first brought to light the great doctrinal differences between the two churches which claimed to be evangelical. It is not true, as was later contended.., that there had been agreement in all essential points of evangelical doctrine until Luther's stubborn insistence on his exposition of the words, "This is my body," wrecked the unity which had already been achieved. The Sacrament of the Altar was rather the point at which, despite every good intention, the utter impossibility of reconciling two fundamentally different conceptions of Revelation and Gospel were clearly demonstrated... What was really at stake was revealed during the Marburg Colloquy in 1529, when Oecolampadius exhorted Luther not to think so much about the humanity of Christ, but rather to lift up his thoughts to His divinity. Luther replied that he knew and honored no other God than the one who became man. And this God is present in the Sacrament just as substantially as He was born of the Virgin. Apart from Him there is no God who can save us. Consequently the humanity of the Lord dare not be underestimated or neglected... Consequently, Luther's insistence on the Real Presence of the Body and Blood of Christ in the Sacrament is at the same time an insistence on the reality of the Incarnation."
Sadly, latter generations have failed to appreciate the intimate theological relationship between the Sacrament and other areas of doctrine. For example, the ELCA, since 1997, has been in "full communion" with several Reformed churches that do not share Luther's insistence on the Real Presence, meaning that Reformed ministers can now preside over Lutheran altars. That such an arrangement is considered generally acceptable is an indication that the Sacraments have a diminished standing in both churches, such that it's not considered important what we or other Christians believe about the Lord's Supper. Apparently, "it is enough" if we all agree to simply ignore our differences and treat our confessional heritage like trivia. Sasse's book is valuable corrective to this trend, because it reminds us how vitally important a correct understanding Lord's Supper was to the Reformers. There can be no unity where there is disunity about the Sacraments.