Crypto-Calvinism is a term for intra-Protestant, indeed intra-Lutheran, theological fights during the decades just after the death of Martin Luther. It denotes what was seen as a hidden ("crypto" from "kryptein", Greek for "to hide") belief in Calvinism, i.e. the doctrines of John Calvin, by members of the Lutheran church, which - since the Marburg Colloquy of 1529--had split, still under Luther himself, from the Swiss Reformed Church then headed by Ulrich Zwingli.
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