The history of the King James Version's dependence on the Textus Receptus
When using the King James Version [KJV] the Bible, it is apparent that in some verses there are major differences between the KJV translation and all modern translations*.
The New King James Version [NKJV] should not really be considered a modern version. The NKJV's New Testament wording always corresponds exactly with the KJV, because both the NKJV and the KJV are based the same Greek texts.
The KJV's New Testament was based upon Erasmus' Greek text as modified by Stephanus and Beza. The NKJV's New Testament was based primarily upon Erasmus' Greek text as modified by Stephanus and Beza, but its translators also consulted the so-called Majority Text.
However unlike the original KJV, the NKJV does not include the Apocrypha. Though the NKJV provides a modern English rewording of the KJV wording, the NKJV still has all of the same errors that the KJV derived from Erasmus' Greek New Testament, which is plagued with corrupt readings... Below are three examples of corrupt texts in the KJV and NKJV. In all three verses, Erasmus' Greek New Testament text was based upon copies of the Latin Vulgate, not on any ancient Greek texts. In other words, the corruption of these verses had no support in any Greek texts prior to 1516...
Truly major differences between the KJV and modern translations of the New Testament are primarily due to the inaccuracy of the so-called Textus Receptus [TR], the Greek text upon which the KJV's New Testament was based. According to Bruce Metzger, the TR primarily resulted from the work of a Dutch Roman Catholic priest and Greek scholar by the name of Desiderius Erasmus, who published his first Greek New Testament text in 1516. The first edition of Erasmus' text was hastily and haphazardly prepared over the extremely short period of only five months. That edition was based mostly upon two inferior twelfth century Greek manuscripts, which were the only manuscripts available to Erasmus "on the spur of the moment".
The Greek New Testament project was seen by its publisher, Johann Froben, as a considerable commercial opportunity. Accordingly Froben expeditiously negotiated with Erasmus, who had already nobly intended to produce a Greek-Latin parallel text New Testament for the primary purpose of allowing Latin readers to become better acquainted with the original New Testament text, which he wanted to approximate as best as possible.
Froben rushed Erasmus' first edition text to market, in his attempt to get it into circulation ahead of the much more methodically prepared Complutensian Polyglot Bible, which was due to be published soon. In contrast to the five months that Erasmus used to hurriedly put his text together and get it printed and circulated, the Complutensian text required eighteen years of careful preparation before its first edition appeared. Erasmus himself said in a letter in Latin in 1516 that this first edition had been "praecipitatum verius quam editum," -- more precipitated than edited.