QUESTION: How did Elector Joachim II of Brandenburg definitively confess, and publicly testify to, his conversion to Lutheranism in 1539?
The elector at long last was ready to take the final step and officially introduce his church order in Brandenburg. He did so by communing publicly in both kinds on All Saints Day, 1 November 1539, at Spandau’s St. Nicolai Church, together with the Protestant nobility from the neighboring Teltow, Havelland, and Barnim regions. The celebrant of this first authorized evangelical mass in the Mark was none other than Bishop Matthias von Jagow who had long been sympathetic to the new faith. A day later, on All Souls Day, an evangelical communion also was offered in Cölin on Spree to the city’s magistrates and burghers. The new “Order of the Mass” as prescribed by Joachim’s ordinance, however, was quite conservative. Much of the Catholic pomp and ceremony including the elevation of the elements was retained. ... Yet in spite of many traditional liturgical embellishments its central teaching was justification by faith, the very heart of Reformation doctrine. “First and foremost,” Joachim insisted, “it is our desire that Christ Jesus, our Redeemer, Beatifier, and Savior be preached – that through faith in Him alone we are saved, without any merit of our own.” This is “the main article and summary of the entire gospel which must be purely taught ... anything opposing it or detracting from it must be eliminated in our lands.” But, eager to maintain the continuity with the old church, Joachim added that “old Christian usages and ceremonies, insofar as they are untainted and not abused, and do not contradict the article of justification, can be retained.” These ceremonies, he explained, are of secondary importance; “they are pleasant and useful, but kept solely for embellishment and discipline.” Luther, Melanchthon, and Justus Jonas all endorsed the elector’s ordinance and quickly responded with congratulatory messages. Luther lauded especially the evangelical thrust of Joachim’s preamble... (Bodo Nischan, Prince, People, and Confession: The Second Reformation in Brandenburg [Philadelphia: University of Pennsylvania Press, 1994], pp. 20-22)
ANSWER: By receiving the Lord’s Supper in a Lutheran Communion service.
QUESTION: How did Elector Johann Sigismund of Brandenburg definitively confess, and publicly testify to, his conversion to Calvinism in 1613?
On Christmas Eve [Martin] Füssel conducted a brief penitential service for those intent on communing with the elector. He “preached in the cathedral church here and made it knowne to the auditorie all that...on the next day, it being the Nativity of our Lord, the Elector would celebrate the communion according to Christ,” noted [English ambassador Stephen] Lesieur. The communion itself, with Füssel and [Solomon] Finck serving as officiants, was patterned after the Palatinate rite. [Simon] Gedicke, who evidently witnessed what happened, was aghast and reported in great detail to his friends in Saxony what he had seen in the Dom: “Not far from the altar a communion table, covered with a white velvet cloth, had been placed. ... On the table lay a long cake, already cut, so that Füssel could easily break off one piece after another and place it into the hands of each communicant ... There was no consecration as we know it. No Lutheran hymns were sung, only [Ambrosius] Lobwasser’s [metered Psalm] songs. ... About fifty people communed: first the English ambassador, then the elector of Brandenburg and Margrave Johann Georg, his regent.” These were followed by the elector’s privy councillors (Pruckmann, Pistoris, Dieskau, Bellin), the English ambassador's retainers, and then the remaining worshippers. There no longer could be any doubt now; the service confirmed what many had suspected for some time; the elector was a Calvinist. (Bodo Nischan, Prince, People, and Confession: The Second Reformation in Brandenburg [Philadelphia: University of Pennsylvania Press, 1994], pp. 93-94)
ANSWER: By receiving the Lord’s Supper in a Calvinist Communion service.