The question itself seems to make some unwarranted assumptions. As a non-Trinitarian, I support the Received Text (Textus Receptus) and/or the Majority Text. There is no need to think that the revised versions, as meddled with by Westcott and Hort and others, are either more accurate, or necessary to a proper understanding of God the Father and the Son of God.
Jesus taught that the Father was in him. He did not, however, teach that he was the Father. None of the passages touching on the deity of Christ say that it was Christ himself who was God--and, as far as I know, this holds true regardless of the manuscript in question. Many seem to think that "son of God" is the same as "God." But this is neither true in English, nor in Greek. The reference to John 1:18 is an interesting case in point--the alteration is that which changed "son" to "God" such that the ESV, for example, has translated it as "No one has ever seen God; the only God, who is at the Father's side, he has made him known." This is a ridiculous translation, and contradicts the rest of the book of John which identifies the Father as God. If "the only God" is "at the Father's side," then, obviously, the Father cannot be God. Therefore, the corruption is easy to identify, because it is a corruption which will introduce a contradiction.
The word "son" has a meaning, and the expression changes in its significance if this word is dropped. If the full expression were "the son of the Father," dropping "Father," and saying just "the son," would change its meaning very little, but dropping "son," and saying just "the Father," would change it completely.
The son of the Father = the Son
The son of the Father ≠ the Father
The changes made in the modern revisions with reference to Christ, his lordship, and his identity, are both unnecessary and specious. It is these changes which constitute a corruption of the text, and not the other way around. Nothing is "preserved" in the critical text, but rather it is destroyed.
The Catholic church, never one to be shy about its accomplishments, publishes quite openly regarding the changes it made to the Biblical manuscripts. The work of editing those manuscripts was documented during the late nineteenth century / early twentieth century1.
Catholic Revisions
Here is what they say about these manuscripts.
(2) Ancient Versions
Several are derived from original texts prior to the most ancient Greek MSS. These versions are, following the order of their age,
Latin, Syriac, Egyptian, Armenian, Ethiopian, Gothic, and Georgian.
The first three, especially the Latin and the Syriac, are of the
greatest importance. (I) Latin version.—Up to about the end of the
fourth century, it was diffused in the West (Pro-consular Africa,
Rome, Northern Italy, and especially at Milan, in Gaul, and in Spain)
in slightly different forms. The best known of these is that of St.
Augustine called the “Itala”, the sources of which go as far back as
the second century. In 383 St. Jerome revised the Italic type
after the Greek MSS., the best of which did not differ much from the
text represented by the Vaticanus and the Sinaiticus. It was this
revision, altered here and there by readings from the primitive Latin
version and a few other more recent variants, that prevailed in the
west from the sixth century under the name of Vulgate. (2) Syriac
Version.—Three primitive types are represented by the Diatessaron of
Tatian (second cent.), the palimpsest of Sinai, called the Lewis codex
from the name of the lady who found it (third cent., perhaps from the
end of the second), and the Codex of Cureton (third cent.). The Syriac
Version of this primitive epoch that still survives contains only the
Gospels. Later, in the fifth century, it was revised after the Greek
text. The most widespread of these revisions, which became almost
the official version, is called the Pesitta (Peshitto, simple,
vulgate); the others are called Philoxenian (sixth cent.), Heraclean
(seventh cent.), and Syro-Palestinian (sixth cent.). (3) Egyptian
Version.—The best-known type is that called Bohairic (used in the
Delta from Alexandria to Memphis) and also Coptic from the generic
name Copt, which is a corruption of the Greek aiguptos Egyptian. It
is the version of Lower Egypt and dates from the fifth century. A
greater interest is attached to the version of Upper Egypt, called the
Sahidic, or Theban, which is a work of the third century, perhaps
even of the second. Unfortunately it is only incompletely known as
yet.
These ancient versions will be considered precise and firm witnesses of the Greek text of the first three centuries only when we have
critical editions of them; for they themselves are represented by
copies that differ from one another. The work has been undertaken and
is already fairly advanced. The primitive Latin version had been
already reconstituted by the Benedictine D. Sabatier (“Bibliorum
Sacrorum latinm versiones antiquae seu Vetus Italica”, Reims, 1743, 3
vols.); the work has been taken up again and completed in the
English collection “Old-Latin Biblical Texts” (1883-1911), still in
course of publication. The critical edition of the Latin Vulgate
published at Oxford by the Anglicans Wordsworth and White, from 1889
to 1905, gives the Gospels and the Acts. In 1907 the Benedictines
received from Pius X the commission to prepare a critical edition of
the Latin Bible of St. Jerome (Old and New Testament). The
“Diatessaron” of Tatian is known to us by the Arabic version edited in
1888 by Msgr. Ciasca, and by the Armenian version of a commentary of
St. Ephraem (which is founded on the Syriac of Tatian) translated into
Latin, in 1876, by the Mechitarists Auchar and Moesinger. The recent
publications of H. Von Soden have contributed to make the work of
Tatian better known. Mrs. A. S. Lewis has just published a comparative
edition of the Syriac palimpsest of Sinai (1910); this had been
already done by F. C. Burkitt for the Cureton codex, in 1904. There
exists also a critical edition of the Peshitto by G. H. Gwilliam
(1901). As regards the Egyptian versions of the Gospels, the recent
edition of G. Horner (1901-1911, 5 vols.) has put them at the
disposition of all those who read Coptic and Sahidic. The English
translation, that accompanies them, is meant for a wider circle of
readers.
Notice how, strangely, the Catholic encyclopedia considers these other-language manuscripts to be more "original" than "the most ancient Greek MSS"? This was because the Latin, etc. were in their own hands and were edited/altered by them, as they document in the record. Notice how many times they reference a "revision" and speak of the work of correcting and revising these texts.
When they say "The work has been undertaken and is already fairly advanced," they refer, of course, to a work that is now completed, as this encyclopedic entry is about a century old. They were documenting what was taking place in the late nineteenth century and early twentieth century. It was during about this time that Westcott and Hort did their work. It is interesting that the Catholic record does not mention their names, nor does it record who was doing the work they referenced.
Clues from the Dead Sea Scrolls
Dr. Bill Barrick, a Hebrew professor who has served as a consultant to nine Bible-translation projects, explains that the scribes who copied the Biblical manuscripts regarded them as so sacred that even when they had made copying errors, and were forced to reject the flawed manuscript, they would not burn it, nor destroy it. Because it contained portions of the sacred scripture, they still handled it carefully. They placed these manuscripts in earthen jars, and gave them an honorable burial. The Dead Sea Scrolls, found in Qumran, are these flawed manuscripts. We know they are incomplete because the Jews considered the name of God to be so sacred that a separate scribe would write it, and there are many blanks in the manuscripts where the name was not yet added.
The Dead Sea Scrolls are considered to be as much as 1000 years older than the Masoretic texts used to translate most Bibles today (certainly any Bible pre-dating their discovery in about 1947). They were well preserved in their earthen vessels within those desert caves.
The fact that these manuscripts have many flaws, and yet appear older, is of considerable interest in the discussion of which manuscripts are actually superior: those appearing "more ancient," or those which appear newer, likely because they were worn out from being copied and were replaced. The ones chosen to be used, and copied, would certainly be the ones deemed superior by the scribes, who had very strict policies with the work of copying. Errors were not tolerated. Even if a "typo" had crept into the text, it was forbidden to correct it--the scribes would make a marginal note to indicate if they had observed another version of the manuscript to have had a different spelling, but they would not make any change to the manuscript being copied. In many cases, those other manuscripts referenced have not survived, and these marginal notes are all we have to help us understand the possible changes as well as the strict culture among the scribes of preserving the text exactly.
Conclusion
A careful review of the manuscripts will show that in most cases the "anti-Trinitarian" versions are actually the most reliable. The "corruptions" are those of the "critical text" line, and this line is well-known for its origination in Egypt. The codex siniaiticus, codex vaticanus, and codex alexandrinus, the three dominant minority texts used in the modern translations, are all part of the "critical text" which Westcott and Hort promoted following their edits.
1 A footnote on the Catholic encyclopedia website says: "Catholic Answers is pleased to provide this unabridged entry from the original Catholic Encyclopedia, published between 1907 and 1912."
