Heresy was treated harshly by both Protestants and Catholics across Europe in the 16th century. Michael Servetus fell into this category, having propounded rejection of fundamental Christian doctrines, such as original sin and the Trinity. He also taught that devils possessed deity. Calvin knew that Servetus’ views would lead to execution, but in a letter to Farel he expressed his hope that the severity of Servetus’ punishment would be mitigated. Nonetheless, the Genevan council tried and convicted Servetus for heresy before burning him at the stake.