This passage condemns anyone who adds to or subtracts from the prophecy "of
this book." It is translated, in the King James Version:
18: "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:"
19: "And if any man shall take away from the words of 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."
The implication is that anyone who declares that a prophecy of "this book"
is invalid will not attain heaven, but spend eternity
being tortured in Hell.
Debate exists about the precise meaning of the phrase "this book"
which is repeated four times in the above verses:
Many conservative Christians, noting that the passage is located
within two verses of the end of Revelation and thus the end of the Bible,
conclude that "this book" is in fact the Bible itself -- both the
Hebrew Scriptures (Old Testament) and the Christian Scriptures (New
Testament).
Others note that there is a general consensus that Revelation was
written very late in the 1st century CE, perhaps circa 95 CE. However, the
first known individual to specify a list of books that matches our present
Bible was Pope Damasus, (304-384 CE). 1 He proclaimed
this list in 374 CE. His canon was later approved by Council of Rome
in 383 CE and reconfirmed at the Councils of Carthage in 393, 397 and 419
CE. 2 Thus, at the time that Revelation was written,
the Bible did not exist as a book, and would not be created for almost two
centuries. Thus, many theologians feel that the phrase "this book"
refers to the book of Revelation only, and not to the entire Bible.