Is the King James Bible the only reliable Bible?
The work of Bible translation is very complicated, and misunderstanding easily arises. We do not have the original Hebrew/Aramaic Old Testament or the original Greek New Testament as written by inspired men of God. What we have is an Old Testament in Hebrew/Aramaic and thousands of Greek manuscripts of part or all of the New Testament painstakingly copied and passed on to us through the centuries.
There are differences in the Greek manuscripts such as minor issues of punctuation, spelling, word order, certain verses included in some manuscripts and not in others, etc., but none of these differences affect any of the major doctrines of our Christian faith.
Some people prefer the King James translation because they have been familiar with it, often from childhood. Others prefer modern translations because they are more easily understood. Also, modern translators have the advantage of using many older Greek manuscripts of the New Testament discovered since the King James translation was made. Most scholars consider these older manuscripts more reliable than the few later manuscripts available to those who translated the King James Bible.
It is also helpful to remember that, while King James "authorized" a particular translation for the Church of England in the 17th century, it is no more authoritative for us today than any other translation. It was highly criticized in its day by those who preferred earlier translations, and it went through a number of revisions. The King James Version most widely used today is the 1769 revision.
People sometimes pick up two translations and expect them to be word-for-word the same. When they find words "missing" or changed, they think something sinister has happened. In reality, both can be perfectly faithful translations of the original language. The basic structures of languages differ from one another, and translation is not just a matter of taking a Greek sentence and finding English words to match. A helpful resource on this topic is the book “How To Read The Bible For All It’s Worth” by Gordon Fee and Douglas Stuart.
Do not get caught up into a divisive and fruitless controversy over which of many good translations is best. Instead, consider using a number of them in your study and reading, and join in prayer that all peoples in all countries of the world might soon have the Word of God in their own language.