Most King James Bible believers do not believe that a person has to believe the King James Bible to be saved.
Now, that said, I believe a Modern Bible can lead a person astray in believing false doctrines because that is what they teach.
Textual Critics who make their own Bible translation are in danger with the Lord because they are adding and taking away from God's true words. So if you are creating a Modern Bible, I would say you are in trouble with the Lord. In other words, there has to be a perfect Word in order for God to give us a warning to not add or take away words from the prophecy of this book (Revelation 22:18-19). Even if you wanted this warning to be solely about the book of Revelation, it does not help you because Modern Bible creators have altered the book of Revelation, as well.
If you go back to my post
here, you will see 25 changes in Modern Bibles by way of comparison to the King James Bible.
These changes are for the worse and not for the better. These are glaring problems that change doctrine and are big things to swallow (i.e., which would be like swallowing a camel). We are not talking about what may look like a minor supposed error in the KJV (straining at gnats), or a word being archaic in the King James Bible. There are serious problems in the Modern Bibles and thus it disqualifies them as being the true Word of God. God does not make mistakes. His promise to preserve His words perfectly is true (Psalms 12:6-7).
I have come up with 101 Reasons for the KJB in being the Pure Word of God. I also come up with 10 Main Categories that support the King James Bible is the Word for today (See
here).
Most Modern Greek Theological Scholars do not even know how to order a pizza in Greek. So why would I trust your Greek?
Here is the difference of why the KJB is superior. A top Greek grammarian Professsor Georgios Babiniotis says there is a solecism in "the Greek grammar" if 1 John 5:7 is removed, as well. This professor lives in Greece, and he speaks the native language and is the former Minister of Education and Religious Affairs of Greece. See this video below to learn more.