The Church is that visible society of men upon earth which was founded by Jesus Christ, guaranteed by Him to exist all days until the end of the world, and sent by Him to teach all nations with His own authority. It is one definite society for man’s spiritual good, and its members are bound together by the profession of the same and complete Christian faith, by the same Sacraments and worship, and by submission to the same spiritual authority vested in the successors of St. Peter— the present successor being the Bishop of Rome.
Nature of the Church, Question 325 from Radio Replies Volume I Copyright © 1938 (by Rev. Dr. Leslie Rumble, M.S.C. and Rev. Charles Mortimer Carty).