MY friend Steve Rafalsky commented on the issue:
There are two aspects to discussions such as this: the first being, a) “Endeavouring to keep the unity of the Spirit in the bond of peace” (Eph 4:3), and “be likeminded, having the same love, being of one accord, of one mind. Let nothing be done through strife or vainglory; but in lowliness of mind let each esteem other better than themselves” (Phil 2:2,3). One should note that these are apostolic commands, not optional suggestions!
The second aspect is, b) “speaking the truth in love” (Eph 4:15), “ye should earnestly contend for the faith which was once delivered unto the saints” (Jude 3), and, “Man shall…live…by every word that proceedeth out of the mouth of God” (Matt 4:4). These also are commands.
There may be a strong tension between these two sets of commands, and it is upon us to resolve it while maintaining obedience to both. A difficult line to walk, to be sure, but it can be done.
I would prefer the scholarly way of resolution, and such I shall do here. I will quote from two excellent scholars on this topic, Harvard text critic Edward F. Hills, and Anglican scholar John William Burgon. Hills first, from his work, The King James Version Defended, chapter 5, pp 132-133:
Luke 23:34a “Then said Jesus, Father forgive them, for they know not what they do.”
This disputed reading is found in the vast majority of the New Testament manuscripts, including Aleph, A, C, L, N. and also in certain manuscripts of the Old Latin version, in the Curetonian Syriac manuscript and in the Peshitta, Harclean, and Philoxenian versions. It is also cited or referred to by many of the Church Fathers, including the following: in the 2nd century, Tatian (60) Irenaeus; (61) in the 3rd century, Origen; in the 4th century, Basil, Eusebius, and others. The reading is omitted, on the other hand, by the following witnesses: Papyrus 75, B. D, W. Theta, 38, 435, certain manuscripts of the Old Latin version, the Sinaitic manuscript of the Old Syriac version, and the Coptic versions (with the exception of certain manuscripts). Cyril of Alexandria is also listed as omitting the reading, but, as Hort admitted, this is only an inference.
Not many orthodox Christians have agreed with Westcott and Hort in their rejection of this familiar reading which has become hallowed by many centuries of tender association. But these critics were nevertheless positive that this petition ascribed to Christ was not part of the original New Testament text but was interpolated into the Western manuscripts early in the 2nd century. This prayer of our Saviour for His murderers, they insisted, like the agony and bloody sweat, was “a fragment from the traditions, written or oral, which were, for a while at least, locally current beside the canonical Gospels, and which doubtless included matter of every degree of authenticity and intrinsic value…. Few verses of the Gospels,” they continued, “bear in themselves a surer witness to the truth of what they record than this first of the Words from the Cross: but it need not therefore have belonged originally to the book in which it is now included. We cannot doubt that it comes from an extraneous source.” (62)
Westcott and Hort’s theory, however, is a most improbable one. This prayer of Christ would be interpreted as referring to the Jews and, thus interpreted, would not be something likely to have been added to the Gospel narrative by 2nd-century Christian scribes. For by that time the relationship between Jews and Christians had hardened into one of permanent hostility, and the average Christian would not have welcomed the thought that the Jews ought to be forgiven or that the Saviour had so prayed. Certainly the general tone of the 2nd-century Christian writers is markedly anti-Jewish. The Epistle of Barnabas, written about 130 A.D. reveals this emphasis. “In no other writing of that early time,” Harnack tells us, “is the separation of the Gentile Christians from the patriotic Jews so clearly brought out. The Old Testament, he (Barnabas) maintains, belongs only to the Christians. Circumcision and the whole Old Testament sacrificial and ceremonial institution are the devil’s work.” (63)
For these reasons Harnack (1931) was inclined to accept Luke 23:34a as genuine and to believe that this prayer of Christ for His murderers was omitted from some of the manuscripts because of the offense which it occasioned many segments of the early Christian Church. “The words,” he observed, “offered a strong offense to ancient Christendom as soon as they were related to the Jews generally. Indeed the connection, viewed accurately, shows that they apply only to the soldiers; but this is not said directly, and so, according to the far-sighted methods of the exegesis of those days, these words were related to the enemies of Jesus, the Jews generally. But then they conflicted not only with Luke 23:28 but also with the anti-Judaism of the ancient Church generally…. The verse ought in no case to be stricken out of the text of Luke; at the very most it must be left a question mark.” (64)
Streeter also and Rendel Harris (65) were friendly to the supposition that Christ’s prayer for His murderers was purposely deleted from Luke’s Gospel by some of the scribes due to anti-Jewish feeling. But again it is not necessary to imagine that orthodox Christian scribes were the first to make this omission. It may be that Marcion was ultimately responsible for this mutilation of the sacred text. For, as Williams observes, “Marcion was anti-Jewish in all his sentiments.” (66) It is true that, according to Harnack’s analysis, Marcion still included this prayer of Christ in his edition of Luke’s Gospel (probably relating it to the Roman soldiers), (67) but some of his followers may have referred it to the Jews and thus come to feel that it ought to be deleted from the Gospel record. (Source; notes)
And then Burgon, from his The Revision Revised, pp 82-85 (for the footnotes see here, starting at fn 242):
Next in importance after the preceding, comes the Prayer which the Saviour of the World breathed from the Cross on behalf of His murderers (S. Luke xxiii. 34). These twelve precious words,—(“Then said Jesus, Father, forgive them; for they know not what they do,”)—like those twenty-six words in S. Luke xxii. 43, 44 which we have been considering already, Drs. Westcott and Hort enclose within double brackets in token of the “moral certainty” they entertain that the words are spurious.242 And yet these words are found in every known uncial and in every known cursive Copy, except four; besides being found in every ancient Version. And what,—(we ask the question with sincere simplicity,)—what amount of evidence is calculated to inspire undoubting confidence in any existing Reading, if not such a concurrence of Authorities as this?… We forbear to insist upon the probabilities of the case. The Divine power and sweetness of the incident shall not be enlarged upon. We introduce no considerations resulting from Internal Evidence. True, that “few verses of the Gospels bear in themselves a surer witness to the Truth of what they record, than this.” (It is the admission of the very man243 who has nevertheless dared to brand it with suspicion.) But we reject his loathsome patronage with indignation. “Internal Evidence,”—“Transcriptional Probability,”—and all such “chaff and draff,” with which he fills his pages ad nauseam, and mystifies nobody but himself,—shall be allowed no place in the present discussion. Let this verse of Scripture stand or fall as it meets with sufficient external testimony, or is forsaken thereby. How then about the Patristic evidence,—for this is all that remains unexplored?
Only a fraction of it was known to Tischendorf. We find our Saviour’s Prayer attested,—
In the IInd century by Hegesippus,244—and by Irenæus:245—
In the IIIrd, by Hippolytus,246—by Origen,247—by the Apostolic Constitutions,248—by the Clementine Homilies,249—by ps.-Tatian,250—and by the disputation of Archelaus with Manes:251—
In the IVth, by Eusebius,252—by Athanasius,253—by Gregory Nyss.,254—by Theodoras Herac.,255—by Basil,256—by Chrysostom,257—by Ephraem Syr.,258—by ps.-Ephraim,259—by ps.-Dionysius Areop.,260—by the Apocryphal Acta Pilati,261—by the Acta Philippi,262—and by the Syriac Acts of the App.,263—by ps.-Ignatius,264—and ps.-Justin:265—
In the Vth, by Theodoret,266—by Cyril,267—by Eutherius:268
In the VIth, by Anastasius Sin.,269—by Hesychius:270—
In the VIIth, by Antiochus mon.,271—by Maximus,272—by Andreas Cret.:273—
In the VIIIth, by John Damascene,274—besides ps.-Chrysostom,275—ps. Amphilochius,276—and the Opus imperf.277
Add to this, (since Latin authorities have been brought to the front),—Ambrose,278—Hilary,279—Jerome,280—Augustine,281—and other earlier writers.282
We have thus again enumerated upwards of forty ancient Fathers. And again we ask, With what show of reason is the brand set upon these 12 words? Gravely to cite, as if there were anything in it, such counter-evidence as the following, to the foregoing torrent of Testimony from every part of ancient Christendom:—viz: “b d, 38, 435, a b d and one Egyptian version”—might really have been mistaken for a mauvaise plaisanterie, were it not that the gravity of the occasion effectually precludes the supposition. How could our Revisionists dare to insinuate doubts into wavering hearts and unlearned heads, where (as here) they were bound to know, there exists no manner of doubt at all?
It is a real shame the word of God is being assaulted in this manner; such an attempt at excision is – to me – as grievous as the removal of “broken” in 1 Cor 11:24’s record of Jesus’ words, “Take, eat: this is my body, which is broken for you”. It is upon those who hold to the Reformation standard to adorn their conversation with grace, wisdom, and scholarship.
Matthew Winzer writes in response:
“What do you do when you have a text that is highly questionable?”
That is the question Dr. White poses. But all he has brought for evidence to prove that it is “highly questionable” is the omission of the saying in certain mss. That is it! He cannot tell us who wrote these mss. or what function they served. He categorises them, without any evidence, as “New Testament mss.” And there is the problem. He does not know that the mss. which omit the saying are in fact “New Testament mss.” The word “New Testament” is a canonical term which assumes an authenticity and authority that mss. in and of themselves do not possess. He is borrowing the term “New Testament” in order to give weight to a ms. and claim that a reading is questionable because it is not in a certain ms. There is nothing empirical or evidentially credible about such a claim. It is mere question-begging. He never goes to the trouble to prove what is fundamentally necessary in a case such as this, which is the right of the ms. to be called “the New Testament.” And this of course is the problem which has arisen in connection with strict empiricism and the quest for “evidence.”
The Last Twelve Verse of Mark by D. Burgon
I would only add, being confessional, the WCF cites these verses as a proof text.