Methodism is a denomination of Protestant Christianity that originated from John Wesley's revivalist movement within the Church of England during the early 18th century. He appointed unordained evangelists to travel and preach, and he sought for Protestants to travel and preach outdoors. Wesley was a critic of Calvinism, believing that Christian perfection existed and not predestination, and he said that it was possible for the love of God to reign supreme in people's hearts in their lifetimes, giving them outward holiness. He also said that grace was the way that God maintained his believers, and he encouraged people to experience Jesus personally. Wesley considered his religion to be a part of Anglicanism for the rest of his life, but his 1791 death led to the Methodist movement becoming a new church. The core tenets of Methodism remain assurance of salvation, priesthood of all believers, primacy of scripture, social holiness, missionary zeal, charity, and service to the poor and vulnerable. From 1760 to 1820, the religion grew among the working class of the United States, and it also became the religion of many slaves and African-Americans. Due to their missionary zeal, Methodists have succeeded in spreading their faith to regions across the world, making it one of the most important Protestant denominations.