Without question the language of the King James Version is outdated. In one linguistic situation, however, this is unfortunate for it avoided a communication problem of modern English. Even the New King James Version fails in its communication no doubt based on its desire to bring the Bible into modern English.
Modern English does not distinguish between the 2nd person singular “you” and the 2nd person plural “you.” You refers to both without distinction. The antiquated King James Version uses thee/thou for the singular and ye for the plural, thus recording the distinction that is clear in the original text of the New Testament.
To point out this difference some modern English translations insert a distinguishing term as in the New American Standard Bible rendition of John 4:48, “So Jesus said to him, ‘Unless you people see signs and wonders, you simply will not believe.’” People defines you as plural. Of course, the word “people” is not in the original text but this procedure works well as long as the translators are consistent. Unfortunately this is not always the case. These translators encountered the same problem at John 3:7 and 11 but failed to identify the variance in number:
“Do not marvel that I said to you, ‘You must be born again.’”
“Truly, truly I say to you, we speak that which we know, and bear witness of that which we have seen; and you do not receive our witness.”
The King James Version translators maintained consistency and thereby represented a clearer and more accurate translation at these points:
“Marvel not that I said unto thee, Ye must be born again.”
“Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen; and ye receive not our witness.”
O the wonderful anachronism of the antiquated King James Version!