Maximus the Confessor

Maximus had his right hand cut off and his tongue cut out by Byzantine imperial agents because he wouldn't accept a compromise on Christology. He died in exile on the Black Sea coast. His theology is dense — most people find Maximus the hardest of all the Fathers — but it's also the high water mark of Eastern Christian thought. Every later Orthodox theologian, and most Catholic theologians who took the East seriously, treated him as the test case. The fact that he was tortured by Christians for his theology is a fact the church has never quite known what to do with.