Significantly, Elert placed his discussion of the Lord's Supper after "the person of the reconciler" and "the work of the reconciler" in the fifth part of his Glaubenslehre (his dogmatics), the part entitled "reconciliation." His reasons for doing so centered on the catholic-orthodox-evangelical claim that what one confesses of Christ has implications for what confesses of Christ's Supper and vice versa. (In other words, Luther's debate with Zwingli was a Christological debate, not merely or even centrally a debate about the Lord's Supper.)
(Baptism is addressed in part two of his sixth section, "the changed existence" [Der Existenzwandel], after his analysis of "the church" and before his analysis of "Encouragement [paraclesis] and justification." Elert held that "baptismal fellowship" is already a reality among most western and eastern Christians, since they acknowledge each other's Baptisms as valid. But interestingly, he does not treat the Lord's Supper under "the church.")
The final paragraphs in Elert's discussion of the Lord's Supper (trans. by Martin Bertram as The Lord's Supper Today [CPH, 1973], 46-47) are most helpful for correcting the notion that there must be complete theological agreement in all matters of scriptural doctrine before there can be church fellowship: "It is precisely in the situation of the local congregation that the Lord's Supper fulfills its function as synaxis [participation in Christ and Christ's body, the church] most meaningfully," a synaxis that also has "an eschatological character." This "synaxis" "depends on the Lord's own call--and since it achieves its reality through the food received in this meal--this synaxis is practiced to the extent that Christ's call is obeyed and this food is received... Here, as in the Eucharistic prayer of thanksgiving, God is being asked to grant the synaxis of His church. What this says, first of all, is that the synaxis in the Lord's Supper is not achieved by the mere assembling of Christians. Rather it is the work of Him who calls them together and makes of the many one body."
Who among us LCMSers can state with absolute confidence that one has NOT rightly discerned the body of Christ when one eats and drinks the Lord's Supper in a congregation of the ELCA? How could the LCMS as a political institution ever make that kind of judgment for an individual without at the same time lording over
the individual consciences of others, frustrating the invitation and promise of Christ, and doing violence against his body?
For someone to rule/demand that another Christian (who is not under the restrictions of excommunication) must refrain from communing in such and such a congregation does violence against the body of Christ, does not preserve the communion of all who belong to Jesus Christ, and is an offense against the responsibility of communion that has its basis in the very nature of the Lord's Supper.
The invitation of Jesus that a pastor issues when he/she says the words of institution in Jesus' stead is for all of Jesus's disciples, and no bishop or district president or church body on its own may insert itself between this invitation and those who respond to it in responsible faith.