TS Krobacz,
I assume you are referring to the Book of Mormon, which was sent into the world fulfilling the prophecy of John the Revelator in Revelation 14:6-7 and fulfilling the prophecy of Isaiah in Isaiah 29:4 and 29:18-19.
To me “adds to them” or “takes away from the words” has to do with changing the meaning of the prophecies and the teachings. There are some very clear teachings that have been “taken away from” by lessening the impact of their meaning having to do with becoming like Christ and inheriting a joint throne with Him. See Revelation 3:21 and Revelation 21:6-7. The adversary has had influence in changing those meanings, because it changes an understanding of the purpose of this life, which is described in Revelation 3:18-20.
Another example of a significant change in meaning is found by reading Revelation 3:7 and comparing with Isaiah 22:21-23 and realizing that both of those prophecies are speaking specifically about the Savior, the Son of David, and that the key of David refers to the Savior having power to “open, and none shall shut”, and “shut, and none shall open”. If anyone has changed that meaning to mean someone other than the Savior, then it’s clear to me that they haven’t paid attention to the warning you noted that John was inspired to give about the meaning of the prophecies he gave by revelation to the world.
John also prophesied that a “beast” would have “power” “given him over all kindreds, and tongues, and nations.” (Revelation 13:9) He warned, “If any man have an ear, let him hear.”
That power was temporary, not permanent, but that prophecy tied to the prophecy in Revelation 12:13-14 and 17. It also tied to the prophecy in Revelation 14:6-8.
So when an angel came to earth “having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people”, then for people to take notice of that everlasting gospel and rejoice in its teachings, should not be viewed as a bad thing.
I should also add a clarification about the post you responded to, since I hadn’t had time to make note of the sources of the words of Paul because I just had a minute to briefly respond.
Here are the sources that I had left out of that post:
2 Thessalonians 2:8, 1 Corinthians 3:13, and for the words of the Savior, Luke 17:26-30.
Wishing you peace, and a good day.