From "Answers To Your Bible Version Questions" ©2001 David W. Daniels.
Reproduced by permission
Question: Why are some words in the KJV italicized? I don't see this in other versions. Why don't they do this if it's a good thing to do?
Answer: The italics usually are a simple way of telling us when the word in English is not in the Hebrew or the Greek. There is only one exception to this rule. I will discuss this in a moment.
The King James translators had a simple goal: to communicate God's words in the English language. They were quite honest. When the word they needed to communicate the Greek or Hebrew sentence into English was missing, they wrote the word, but in italics. There are two ways in which this happened.
"And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world." (1 John 4:3)
It is less clear to write, "and this is that of antichrist." "That what?" you will ask. That spirit. To avoid confusion, they supplied in English a word that you could understand from knowing the Greek, but which wasn't directly said in the Bible language.
Where the words were in the original, but they didn't have enough evidence at the time. God's help in preservation of His words is found in an unusual way in 1 John 2:23:
"Whosoever denieth the Son, the same hath not the Father: [but] he that acknowledgeth the Son hath the Father also."
Look at the verse again. This is a bit more complex. The word [but] is not in any manuscript, period. It is needed, however to show the contrast to English readers. That is like the regular italics in the rest of the King James Bible.
But wait! A full 1/2 of this verse is in italics! How could this be? It's simple: the King James translators were very honest. They found some Greek manuscripts at the time that had the verse and others that didn't. But they had enough evidence from other languages that did, and a very good reason why the verse might have been mistakenly removed by a copyist — homoeoteleuton.
That big Greek word simply means, "having the same ending." The phrase "hath the Father" is at the end of both parts of the verse. In Greek it looks like this: As the copyist looked back and forth between the original and his copy, his eye could have skipped to that same phrase at the end of the verse. Thinking he had already written it, he would have moved on, thus leaving out the last part of this verse.
In order to be truthful, the King James translators included the 2nd 1/2 of the verse, because it belongs there. But to be fair with what they had in front of them, they put that 1/2 verse in italics.
The King James Translators Vindicated
But the best part is that history has shown the King James translators correct! As many more minuscule manuscripts (Greek scriptures with all lower-case letters) were found, many more contained the verse. Of course it was found in many early translations. But in the biggest irony for the King James haters: it was even found in the Alexandrian perversions! The pro-Alexandrian "scholars" could not say the King James translators were wrong, since it even appeared in their own corrupt copies!
The Bottom Line
The main point is this: God made sure the King James Bible was not only an accurate and excellent translation of His words in English, He even made sure they were quite honest in their use of italics. Some have even gone so far as to say, "even the italics are inspired." What I will conclude is this: God watched over every word of His Bible in English, the King James Bible (or Authorized Version), to be sure we would have God's preserved words in our powerful and influential language. And this has been confirmed time and again, every time I research what is in the King James Bible.
God bless you as you learn from His preserved, even italicized, words.