Whether your friend accepts it or not, the New King James did use the same texts as the King James, and was intended to be an update (replacing thee's and thou's, etc.) as well as correcting errors within the KJV. The translators also referred to the other manuscripts, not for the purpose of translation, but in order to make note of the differences. I use the NKJ extensively, and that is one of the things that I particularly like about it, that the footnotes show the variations found in the NU, the Majority Text, etc. It is a little like having an NASB right there for comparison.

Meta4

There is no such thing as preaching Christ and Him crucified, unless we preach what nowadays is called Calvinism. It is a nickname to call it Calvinism; Calvinism is the gospel, and nothing else. - C.H. Spurgeon