His teachings that the Bible should be translated into vernacular tongue (In this case Czech), his opposition to Simony (which was wide spread at the time) and the existence of Purgatory lead to him being excommunicated, deemed a heretic and burnt at the stake in 1415.
His teachings about Bible translation, opposition to simony, and belief in Purgatory resulted in his condemnation as a heretic and execution by burning in 1415.