The King James Version (KJV) of the Bible may be the most famous version of the Scriptures. The New King James Version (NKJV) represents an effort to modernize and clarify the original KJV.
Language
The KJV is known for its Old English language, using words like "thee," "ye," "thine" and "thou," while the NKJV uses modern English ("you" and "yours").
History
The KJV is the oldest English version of the Bible, completely translated from the original Hebrew and Greek in 1611. The full NKJV Bible was translated in 1982.
Usage
The NKJV is usually preferred by readers who want a translation that is easier to understand. But Bible purists believe that the KJV is the finest translation that has been, and forever will be, produced.
KJV Only
Some Christians consider the KJV to be the only version of the Bible that can be considered the "inspired word of God." Thus, they are known as "KJV Only" Christians.
Bottom Line
While some Christians are adamant about preferring one translation over another, both are used by English-speaking Christians all over the world. Whether you decide to use the KJV or NKJV is ultimately a matter of personal preference.