A contradictory teaching from Martin Luther where he states the Catholic Church is the true Church, then later takes this back:

"Accordingly, we concede to the papacy that they sit in the true Church, possessing the office instituted by Christ and inherited from the apostles, to teach, baptize, administer the sacrament, absolve, ordain, etc., just as the Jews sat in their synagogues or assemblies and were the regularly established priesthood and authority of the Church. We admit all this and do not attack the office, although they are not willing to admit as much for us; yea, we confess that we have received these things from them, even as Christ by birth descended from the Jews and the apostles obtained the Scriptures from them."

Sermon for the Sunday after Christ’s Ascension; John 15:26-16:4 (2nd sermon) A Sermon by Martin Luther; taken from his Church Postil, 1522. [Taken from volume III:254-271 of The Sermons of Martin Luther]

Luther then later contradicts this with:

"If they excommunicate and persecute us because of our evangelical preaching and our knowledge of Christ, we already have the decision of Christ that they are not the true Church, and their office and all the authority of which they boast cannot avail against us; that rather our teaching and judgments against them shall avail before God in heaven. We are certain, by reason of the test which Christ here applies, that the true Church is with the few who know Christ"

Sermon for the Sunday after Christ’s Ascension; John 15:26-16:4 (2nd sermon) A Sermon by Martin Luther; taken from his Church Postil, 1522.[Taken from volume III:254-271 of The Sermons of Martin Luther]