The NIV and some other Bibles leave out verses. Take for example, Matthew
18:11 is missing in the NIV. I know that it may not have the verse, and
that it does cross refer it to Luke. But in Rev 22:19 it says 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.

I discuss this and a number of other similar questions in my book, Reasons
for Belief: A Handbook of Christian Evidences. You can get a copy at this
website. The manuscript evidence used in creating the NIV was vastly
superior to that available when the KJV was made. In 1609, when the KJV
was created, scholars only had less than ten Greek manuscripts to work
from, and none of them were from before AD 1000. When putting together the
NIV, the editors had thousands of manuscripts, including complete Greek
manuscripts from as early as AD 350, and some even older. The manuscript
evidence to support the NIV makes this translation considerably more
accurate than the KJV. The reason that the NIV does not include Matthew
18:11 is that all the earliest manuscripts do not include this phrase.
Apparently, some sort of copyist inserted this phrase in a misguided
attempt to “fix” Matthew by making it agree with Luke. The creators of the
NIV did not take away from the word. It was an early copier of the New
Testament in Greek who added to the word. You should trust your NIV and
distrust your KJV in general, although there are occasional exceptions to
this rule.

John Oakes, PhD