Part I: The Most Important Aspects
The Trust with which we hold the King James Bible
There are many people, like myself, who have an extensive familiarity and tremendous appreciation for the King James Version of the Bible. There are many churches and individuals who will not use, or cannot trust, any other translation. There are two very good reasons for this which are irrefutable.
The first reason is because the translation is a literal rendering of unprecedented quality by the very best scholarship of that day, as well as the culmination of the life work of many individuals who created the translations on which the KJV was based.
The second reason is that the King James Version has proven itself to be the effective, reliable, Word of God. For over 400 years, it has been used almost exclusively by millions of people throughout their entire lives. It is the only universal standard in the English language.
Familiarity and Memorization
I grew up with the KJV as the only Bible there was. I knew the Living Bible existed, but everyone knew it was a paraphrase, and nobody I knew used it. I was in my 20's before I ever touched another version. All those verses I'm familiar with, hundreds of verses I've memorized, all King James. Over 20 years ago (in 1999), I switched to the NASB (1995) for my primary version, but there's still times I just need to see a verse in KJV.
Uniformity in Services and Teaching
Uniformity is also a thing. I've been in churches where everyone uses the KJV, and I've been in churches where everyone has there own version. The comfort level, and even confidence in Scripture is so much better when everyone is using the same version, and I've never seen a church be exclusive to any other version than King James.
Fundamentalism Characterizes King James Churches
Churchs who demand or practice exclusive use fo the King James Bible are inevitably Fundamentalist churches, that is, they believe in verbal, plenary, inspiration, inerrancy, and authority of Scripture, and are about the business of evangalism, discipleship, prayer and ministry. I don't mind saying that a King James church might be, in 2022, your best bet on finding a church with these characteristics.
It is important to note that there are many solid, fundamentalist churches which are not King James exclusive churches, but my point is that a King James exclusivity is typically an indicator of a fundamentalist church.
The Importance of Literal Translation
Most modern translations are NOT literal translations. The use of 'Dynamic Equivalence' or "Thought-for-Thought" translation style lends itself to selling lots of Bibles. They can be easy to read, they can be written in gender-neutral language, and they can be extremely interpretive, based on the opinions of the editors. While it is true that even rough paraphrases of Scripture can be useful, even unto salvation, this cannot be the preferred method when we believe in verbal inspiration. The doctrine of Verbal Inspiration means that the very words the writers used were inspired of God, not just the conceptual ideas.
There are VERY Few English translations which are Literal, or 'Formal Equivalence' in translation style. The King James Version is. Amoung modern translations our only mainstream choices are the NASB and the ESV versions. Other mainstream modern English versions; the NIV, NLT, CSB, etc. are NOT literal translations, should not be acceptable for institutional use, and should be not be recommended for personal use.
Part II: Manuscripts and Translations
The Highlighted Conflict
The distinction between the Textus Receptus or Critical Text translations is a matter selecting the Greek and Hebrew manuscripts from which we choose to translate the biblical text. Erasmus's Greek text was published in 1516-1522 which was used by Martin Luther for his German Bible, and Tyndale for his English Bible, from which we get the King James Version. Critical text versions don't use this same Greek (although they do use the same Masoretic Old Testament Hebrew), but have tried to compile a more accurate representation of the original writings, using many more manuscript sources. So, the results are different - the content of the Bible varies by source. But the sucker-punch is: There's really very little difference. Anyone who has studied the distinctions will know that differences exist, knows how relatively few there are, and knows that none of the differences have doctrinal impact.
The Hidden Conflict
The much more significant problem with Critical Text Bibles is that there have been (and are) really bad translation issues. Most people don't know how good of a literal translation the KJV really is, and there are few English translations of similar quality. The RSV, for example is infamous for translating 'virgin' as 'young woman' in the prophecy of the Birth of Christ. This is not a text issue, but a poor translation. Many such issues are the fault of poor or biased translation. This is a situation which is getting worse with gender-neutral language and dynamic-equivalent translation becoming the norm. This means that even if we could agree on source texts, we still have to carefully investigate and evaluate the quality of translations - hence the lack of trust of modern translations.
Part III But not 'King James Only' as a Dogma
What Erasmus didn't have
Erasmus didn't have access to the Alexandinus, Sinaiticus, or Vaticanus codexes, the Dead Sea Scrolls, or the Sumarian Pentateuch. He also didn't have 400 years of additional research time. Locking the Bible translation down to text which Erasmus used, and denying all post-1611 scholarship the possibility of improving discernment of the original scriptual texts is not only unacceptable, but incomprehensible.
The 'Specially Preserved' English Version
One claim I've repeatedly encountered from King James Only sources is that the KJV is the particularly/specially preserseved English Bible, as in, the translation is supernaturally correct, as opposed to being inerrant "to the degree that it conforms to the autographs". This claim of divine preservation via the KJV cannot be substantiated from Scripture.
Jesus said that his Words would not pass away - but applying that to written Scripture would mean the Greek and Hebrew, or as profusely communicated all over the world in all the various languages. Applying this promise to uphold an assumed superiority of the KJV translation or the TR manuscripts in particular, is dishonest interpretation.