"With the deaths of his father Joachim Nestor (1535) and father-in-law Sigismund (1548), Joachim [II] turned gradually to the Protestant Reformation. On 1 November 1539, he received Communion under both kinds in Spandau's St. Nicholas' Church, an act that indicated a degree of sympathy with the new religious ideas. However, Joachim did not explicitly adopt Lutheranism until 1555, to avoid open confrontation with his ally, Emperor Charles V.[dubious – discuss][citation needed] Prior to this, Joachim promulgated a conservative church order that was Lutheran in doctrine, but retained many traditional religious institutions and observances, such as the episcopate, much of the Mass in Latin, religious plays and feast days." -- Wikipedia
