Protestantism is a denomination of Christianity. It is the second-largest denomination of Christianity with a total of 800 million to 1 billion adherents worldwide or about 37% of all Christians. It originated with the 16th-century Reformation, a movement against what its followers perceived to be errors in the Catholic Church. Protestants reject the Roman Catholic doctrine of papal supremacy and sacraments, but disagree among themselves regarding the real presence of Christ in the Eucharist and matters of church polity and apostolic succession. They emphasize the priesthood of all believers, justification by faith alone rather than by good works, and the highest authority of the Bible alone in faith and morals. The "five solae" summarise basic theological differences in opposition to the Catholic Church.