From the time of the announcement of the reformation mandate on 6 July 1525, and the church ordination and agenda on 10 December 1525, Lutheranism became the official state religion in the Duchy of Prussia, which remained a fiefdom under the rule of the Polish Crown. Against the background of a complex relationship between the faiths in Prussia during the first half of the seventeenth century, where the main division line no longer ran between the Catholics and the Lutherans, but between the Lutherans and those of the reformist faith, the authoress describes a very interesting case - that of Michael Weida/Weyda (1581- ca.1651), an organist from the Marian church in Gdansk, who in 1623 became organist at Koenigsberg's Knipawa cathedral. An analysis of the polemical print 'Wahrhafftiger Bericht und Verantwortung Michael Weyden auff die ... 121. Lügen-Scharteck des D. Mislenta, Colbii, und seines Anhangs, die sich das Drey-Staedtische Ministerium in Preussen nennen' from 1651, discovered at the British Library in London, allows us to revise the established views and to introduce new factual information into this musician's biography. The dispute between Weyda and the Knipawa pastors - doctor Celestyn Myslenta, cathedral deacon Georg Colbius (1594-1670) and magister Joachim Babatius (d.1656) - was conducted over many years in the form of polemical prints. This dispute, as well as the dismissal of the musician from the post of cathedral organist, his excommunication and exclusion from the Christian community, demonstrate both the religious intolerance and the power of the orthodox Lutheran clergy in Koenigsberg during that period.