Sentence:  But Michael Sept had unmasked him , revealing he had never been a <WSD>bishop</WSD> , but was an Anabaptist , afraid to state his faith , because he knew John Calvin had written a book against their belief that the soul slept after death . 
Meaning of the word marked with <WSD> tags:  a senior member of the Christian clergy having spiritual and administrative authority; appointed in Christian churches to oversee priests or ministers; considered in some churches to be successors of the twelve Apostles of Christ