Constantine became emperor of Rome in 312 A.D. A little later he supposedly embraced the Christian faith for himself and for his empire, in an attempt to bring about the amalgamation of PAGANISM and CHRISTIANITY.
Both admirers and enemies of codices Vaticanus and Sinaiticus readily admit that these two codices are remarkably similar, so similar as to compel one to believe that they were of common origin. Dr. Gregory, a recent scholar in the field of manuscripts, believes that the Vatican and Sinai manuscripts are 2 of Constantine's 50 bibles. He states, "This Manuscript (Vaticanus) is supposed, as we have seen, to have come from the same place as the Sinaitic Manuscript. I have said that these two show connections with each other, and that they would suit very well as a pair of the fifty manuscripts written at Caesarea for Constantine the Great" (Dr. Gregory, The Canon and Text of the NT, p. 345). Also, in his Introduction to Textual Criticism of the NT, Dr. A.T. Robertson states, "Constantine himself ordered fifty Greek Bibles from Eusebius, Bishop of Caesarea, for the churches of Constantinople. It is quite possible that Aleph (Sinai) and B (Vatican) are two of these fifty."
But please remember -- the early Christians REJECTED these manuscripts. So, they went into secret libaries…and there they lay…until they were later dug up as "ancient manuscripts."
So here's what likely happened: the corrupt Alexandrian text (also called the "Egyptian" or "Hesychian" type text) found it's way into Constantine's bible (via Origen and Eusebius), one of which was the Vatican manuscript and another of which was the Sinai manuscript, but they were rejected and "thrown in the closet" by Christians of that day. However, after hundreds of years, they eventually were revived via the Westcott and Hort Greek Text, and finally crept into the new "Bible" versions in your local "Christian" bookstore.
The Devil is sneaky, isn't he??
Therefore, when you hear or read of someone "correcting" the King James Bible with "older" or "more authoritative" manuscripts, you are simply hearing someone trying to use a corrupted, pagan, gnostic, ecumenical, Roman Catholic text to overthrow the God-honored text of the Protestant Reformation and the great revivals.
Does it Really