1. Why was the name Apocalypse placed upon this book? Its principal cause is Christ.
Of the Books of the New Testament, it remains unique and Prophetic. It is inscribed: Ἀποκαλυψις Ἰωάννου τοῦ Θεολόγου, the Apocalypse of John the Theologian. But the Author himself, Revelation 1:1, calls it Ἀποκάλυψιν Ἰησοῦ Χριστοῦ, the Apocalypse, or revelation, of Jesus Christ, which God gave unto Him to be shown unto His servants. That is, because God the Father gave to Christ as the head of the Church that function, to reveal and disclose many secrets to the Church. For, what in the Old Testament goes under the name of vision and prophecy, in the writings of the New Testament is frequently called Revelation, as in 1 Corinthians 14:26; 2 Corinthians 12:7. It is also demonstrated what is the principal cause of this book, namely, Jesus Christ, by the will and decree of God the Father given as a head to the Church, as Prophet, Priest, and King.
Dr. Dilday's Lecture: "Revelation, Part 1"