Revelation 22:18; The Words of the Prophecy of His Book

Revelation 22:18 (KJV)  For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book: 

This is a warning not just to the would-be prophets themselves, who might try to continue prophetic ministries beyond the time of Revelation’s writing, but also to “every man that hearth” , that is, those in the churches who needed to refuse any authority that challenged the divine authority, accuracy, and finality of this prophecy (Ladd). The observation is true that this warning applies specifically to the book of Revelation only, but by extension it entails the termination of the gift of prophecy and the New Testament canon also.

The two uses of “I add” in this verse are a play of two meanings of the word. The former “adds” has the sense of “add” similar to the verb “I add”, cf. Proverbs 30:6, unspeaking of additions to the prophetic substance of this book. The latter – “shall add” – does not have the sense of adding more plagues described in the book (cf. Deuteronomy 7:15). To add to this book’s contents is to incur the visitations which it threatens (Swete).

“The plagues that are written in this book” are, of course, the ones described in connection with the seals, trumpets, and bowls. Anyone guilty of not heeding this monumental warning will not experience the deliverance promised the Philadelphian church (Revelation 3:10), but will remain behind to endure theses plagues (Smith). The bowl-plagues are perhaps more directly in view, but this series presupposes the plagues that went before them.

[Robert L. Thomas, Revelation 8-22 – An Exegetical Commentary, Moody 1995, 517-518]