Crypto-Protestantism is an historical phenomenon that occurred on the territory of the Habsburg Empire. It describes the attempt made after the Protestant Reformation to regain for Catholicism parts of the Empire that had become Protestant. The Protestants in the areas that were re-Catholicised by force strove to retain their own confession inwardly while they outwardly pretended to accept Catholicism. With the 1782 Edict of Tolerance Protestantism was again permitted, and from that time on the Protestants could live their faith openly once more.
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Crypto-protestantism Wikipedia(Text) CC BY-SA