I will just pick out the point Guebert does not pick up on and that I find quite interestingly put: Walther calls "indifferentism" not a confession of a faith but a denial.
Again, some say: "If the Union Church swears itself as much to the Symbols of the Lutheran and of the Reformed Church, so far as both agree with the other, but in points of difference goes back to the Scriptures, thus the Union Church thereby is at least justified against the accusation that it is confessionless and therefore is no church, or no heretical church, rather only a body held together by the bond of indifferentism. I answer: The commonality of several mutually contradictory and mutually condemning Symbols, which only theologians can find so deeply grounded therein, to declare for the confession of a churchly fellowship is so completely contrary to the nature and goal of an ecclesiastical confession that it requires no proof. Such a declaration salvages only the appearance of a confession, but builds only a covering for Gallionism (Acts 18:12-17) [i.e., indifference to doctrine'. There is no doubt that a Lutheran (or even a Reformed person), who in this manner accepts both he Lutheran and Reformed confessions, instead of confessing his faith, disgracefully denies it. Those of the Union Church have appeared to sense this, therefore they have partly tired of finding and establishing the consensus of both Symbols...
..And whoever permits such doctrines to be treated as open questions surrenders the fortress of the Confession of our Church and is in reality no loyal Lutheran.
... Only a skeptic, who is always learning and never coming to the truth, despairs of ever finding the truth and will maintain "Men have written this and therefore it must contain error." But if error should really be found in our Symbols, we would be the first to pass the death sentence on them. But we defy the whole world to point out an error in doctrine in our Book of Concord. for the past three hundred years all the enemies of our Church have tried in vain to find an error, but have failed. They have shown, and we admit it, that our Symbols contain points that are contrary to their blind reason; but they have failed to prove that our Symbols contradict Scripture in the smallest point. Now, just as vain and scandalous, a similar attempt has begun by persons who wish to be viewed as nothing less than the most faithful sons of our Church. they seek to point out that the voice of our spiritual mother in her public Confessions is in part the voice of error. But they will demonstrate nothing more than that they are bastards who, because they do not believe the holy divine Scriptures, besmirch the church as a temptress who confesses what she has found in the Scriptures as her heart's faith.
Strong words on a subject of vital importance.