I will note that 'The Great Commission' a poorly attested addition and arguably late addition to Matthew's Gospel[.]I'm not a textual scholar, so I'm not equipped to refute this the hard/scholarly way. Fortunately, however, one of the nice things about having an internet is that there are always plenty of them lying around, ready for citation. And in this case, Derek Olsen, who is such a scholar, saw this passage first. And he doesn't think much of this assertion:
On the strength of the actual evidence, then, we’ve got to conclude that, contra the starting claim, the Great Commission in its familiar form is very well attested textually and there is only one hint read through a particular philosophical construct to the contrary.Well, I'm not surprised to hear that. There are a very few big disputed passages, such as the Comma Johanneum, the Pericope of the Adultress, and the endings of Mark, and there are a host of shorter passages of some variation, including the doxology of the Lord's Prayer. One hears about the major ones right off if one looks at the subject at all, and in any case if one uses a modern bible the footnotes are going to tell you about the problems. In my RSV Common Bible, the last page of Matthew is utterly bare of textual notes, and the last such note in my NEB New Testament is back at the beginning of chapter 27.
But the whole form of the argument should tell you all you need to know anyway. "It's a late addition" is Protestant/Enlightenment- speak for "this passage is a problem, so I'm going to dismiss it by implying that there is an earlier, more authentic version that leaves it out." It's the Thomas Jefferson approach to theological argument, and the average layman is well-advised to dismiss such arguments out of hand.
I note Derek's comment towards the end about the pattern of trying to cast Trinitarian doctrine as late and therefore an innovation. Unitarianism has been an occupational hazard of Anglican clerics for a quarter millennium, but really in the interest of institutional knowledge, priests and deacons who are going to set aside the creed need to turn in their orders and go find some other job. Restorationism is the road to theological solipsism, and combining it with modern rationalism is the highway to the altar of the Spirit of the Age.