According to Roman Catholic dogma the teaching magisterium is infallible when officially defining faith and morals for believers. One manifestations of this doctrine is popularly known as the “infallibility of the Pope” which was pronounced a dogma in 1870 at Vatican I. This is a major bone of contention between Catholics and Protestants. Roman Catholic authorities define infallibility as “immune from error, i.e., protection against either passive or active deception. This is unresolvable roadblock to any ecclesiastical unity between Roman Catholicism and orthodox Protestantism. For while both sides believe the Bible is infallible, Protestants deny that the church or the pope has an infallible interpretation of it