Wherever it is celebrated, the holy Supper is the congregation’s banner of faith. Just as a person enlists on the side of the army whose flag he supports, so also each Christian places himself on the side of the congregation in whose midst he eats the Supper. If that congregation confesses the true faith, the communicant, by his appearance at the altar, confesses the same faith with it. But if the congregation confesses a false faith, the communicant, by his participation in its celebration of the Lord’s Supper, also confesses the false faith and thus denies the true faith. Therefore, whenever we approach the altar, let us appear before the world as confessors of the crucified Christ, and as true spiritual priests of Him who called us from darkness to His wonderful light. Let us not gather around this banner of faith in the false church, but rather assemble where the true Christ and His whole, pure and genuine Gospel is confessed and preached.
God Grant It: Daily Devotions from C. F. W. Walther p. 333