Adiaphora that is compelled or commanded obscures pure doctrine and true worship...

We also believe, teach, and confess that at a time of confession, when the enemies of God's Word want to suppress the pure doctrine of the Holy Gospel, God's entire church, indeed, every single Christian, but especially the ministers of the Word, as the directors of the community of God [Latin:  God's church], is bound by God's Word to confess the doctrine freely and openly.  They are bound to confess every aspect of pure religion, not only in word, but also in works and actions.  In this case, even in adiaphora, they must not yield to the adversaries or permit these adiaphora to be forced on them by their enemies, whether by violence or cunning, to the detriment of the true worship of God and the introduction and sanctions of idolatry.  For it is written:

For freedom Christ has set us free; stand firm therefore, and do not submit again to a yoke of slavery. (Galatians 5:1)

Yet because of false brothers secretly brought in—who slipped in to spy out our freedom that we have in Christ Jesus, so that they might bring us into slavery—to them we did not yield in submission even for a moment, so that the truth of the Gospel might be preserved for you. (Galatians 2:4-5)

In this place Paul speaks about circumcision, which at that time had become an adiaphoron.  At other times circumcision was observed by Paul.  The false apostles pushed circumcision in order to establish their false doctrine that the works of the Law were necessary for righteousness and salvation.  They missed circumcision to confirm their error in people's minds.  Therefore, Paul says that he would not yield even for an hour, in order that the truth of the Gospel might continue unimpaired.

Paul yields and gives way to the weak concerning food and the observance of times or days.  But to the false apostles, who wanted to impose these on the conscience as necessary things, he will not yield even in matters that are adiaphora.  "Therefore let no one pass judgement on you in questions of food and drink, or with regard to a festival or a new moon or a Sabbath" (Colossians 2:16).  When Peter and Barnabas yielded somewhat in such an emergency, Paul openly rebuske them according to the truth of the Gospel as people who were not acting right in this matter.

This case is no longer a question about outward matters of indifference, which in their nature and essence are free. They cannot produce a command or prohibition that they must or must not be used.  The case presented by Paul is a question, in the first place, about the outstanding article of our Christian faith.  For the apostle testifies, "so that the truth of the gospel might be preserved for you" (Galatians 2:5).  The Gospel is obscured and perverted by such compulsion or command, because such adiaphora are publicly required for the approval of false doctrine, superstition, and idolatry, and for the suppression of pure doctrine and Christian liberty, or at least are abused for this purpose by the adversaries are and viewed this way.
~BOC, FSD, X, 10-14