In AC article I, who is consenting together? Is it individuals? Ministers? Congregations? Whole associations of congregations, acting collectively? The wording provides the answer: individual congregations. Perhaps they were represented by their ministers, or severally by some designated representative, but those commonly consenting to the Lutheran doctrine were essentially congregations of varying size: churches, identified by the marks of the Church.
Here’s another quotation from an ELS father on the topic, distinguishing between the right and authority of a congregation, and the right or authority of a different kind of body.
We take it for granted that the joining together of congregations ought only take place by orthodox – we do not say those of identical belief – congregations. A merger like that American-Lutheran General Synod is a babel, just another organization of many disunited churches. But orthodox congregations also have to watch with the most extreme diligence that through their joining together and through their adopting a constitution for it, that while they do relinquish a portion of their freedom and independence voluntarily in love and with concern for their own as well as the common good, that they do not, however, transfer to the synod or to the joint-church such rights or such power which the Lord has not only entrusted to the congregations themselves, but whose exercise by themselves is the best guarantee for the preservation of the pure faith, for example, installing and removing pastors, practicing church discipline, and adopting hymnbooks and school books. But even less must congregations give to the joint-church or its officers such a power and authority that their decisions should be binding law for the congregations by virtue of a divine authority which should be due them as those who are over them according to the Fourth Commandment – even if their decisions do not conflict with the Word of God. Such a concession on the part of the congregations would make the synod a papacy which would be just as unchristian as the one which reigns in Rome. It would make the congregations slaves of men and would place a yoke upon them which would be heavier to bear and more difficult to remove than that which imprisons and oppresses them in the state churches.
The history of the church past and present shouts its warning! There is the papacy where the congregations, as is well known, are as good as deprived of all their rights. The church, as it is called, that is, the clergy, with the pope at the head, possesses them. As a worldly authority it demands unconditional obedience according to the Fourth Commandment.
The yoke of bondage which laid upon the congregations under the papacy, the Lord lifted through Luther, when as an angel of God this man brought the pure Gospel to light and taught believers to know the Christian liberty which Christ earned for them with his death, and the church learned to know the rights which the Lord of the church had given it in the power of the keys. And even where he agreed that certain of these rights were exercised by the worldly princes because of the congregations’ plight, there, with all the rest of the reformers, Luther is untiring in reminding both them and the congregations of the fact that they did not exercise this power as rulers but only because it was transferred to them by the congregations who possessed it as they who were looked upon as the congregations’ first and leading members because of their power and position. The power which they possessed as rulers only gave them occasion and right to serve the congregations so much more as members of the congregation.
Note. In an opinion from the year 1536 which was also signed by Bugenhagen, Melanchthon, Jonas and Myconius Luther says:
The calling and electing of orthodox servants of the church is properly and primarily not the business of the civil authorities but of the church. When the civil authority is a believer and a member of the church, then he calls not because he is a civil authority but because he is a member of the church; because “my kingdom is not of this world†(Jo. 18:36).
In 1530 Luther writes to Melanchthon:
As sovereign a bishop may impose even less on the church since this would mean fundamentally to mix these two jurisdictions. Should he do it anyway, then he would really be a pseudo-bishop, and we, were we to give in to this, would likewise be guilty of this sacrilege. Against this godlessness and iniquity one must fight and die rather than give in. Of course I speak of the church as a church which has been separated from the political commonwealth. As sovereign, a bishop may impose upon subjects as subjects whatever seems appropriate to him as long as it is godly and permissible; the subjects are required to obey, since under these circumstances they obey not as members of the church but as citizens. For the church is a twofold person in one and the same man . … It is the same as if Pomer forces his Wittenberg parish to abide by his house rule … It is the same as if the emperor ordered all people everywhere to fast, then the members of the church would obey him too, since according to the flesh, the church is under the emperor, but the church does not obey as church. Luther’s Works, American Edition, 49, 385, 386.
The whole address is online.