"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. And if any man shall take away from the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book." - Revelation 22:18,19 (Audio)
The following sermons are on all or some of Revelation 22:18 & 19:
Ulterior Motives? by Rev. Stephen Hamilton
The Perfection of Holy Scripture, by Ian Macleod
Recently Released 'Queen James' Reports to Be First-Ever 'Gay Bible', by Pastor David McManus [2012]
Whosoever Will, by Prof. Herman Hoeksema