Unfortunately I can't say I've got much knowledge about Christian scripture. Regarding its preservation most of what I know is derived from the debate of well-known Christian scripture and textual scholar Dr. Bart Ehrman.
"Bart Ehrman & Daniel Wallace Debate Original NT Lost"
https://www.youtube.com/watch?v=wyABBZe5o68
According to Bart Ehrman:
No complete manuscripts of the Bible from the first, second and third centuries exist.
From early second century only 1 manuscript of the Bible, which has a few verses written on it, has survived.
5,500 manuscripts of the Bible survive, of which 94 % are from the 9th century.
In short what Daniel Wallace said (similar to what you are affirming here) was that due to the vast number of manuscripts that are present and the hundreds of thousands of variances (most are insignificant) in them is a proof that we can reach the original New Testament text.
However, Bart Ehrman is skeptical of this concept or even convinced against it. He seems to believe that the probability of the loss of the original New Testament text is very high by giving an example that it would have taken only a single inaccurate or malicious copier of the New Testament in the first century to corrupt all the manuscripts that are presently available.
I completely agree that hundreds of thousands of the differences in the manuscripts are mostly spelling mistakes and such, as Bart Ehrman admits but according to him some of these differences are significant enough to question core Christian concepts.
In another debate that I was once listening to, the example of 1 John 5:7-8 was given. According to my limited knowledge, this was the verse which most explicitly confirmed trinity in the King James version of the Bible; but, according to new information obtained, in the 1980s its words had to be changed and the present version doesn't appear to be affirming trinity.
It is possible that the present version of the Bible might be the accurate one, I say this because of the "Christian Vs. Muslim" debates that I've listened to, both debaters use the Bible as a source of information. Christians interpret a particular verse a certain way, Muslims another, which is something Muslims apparently have common with nontrinitarian sects of Christianity.
However, as Bart Ehrman argues there is no way of knowing that. There is a reason that textual criticism is still going on, because there is still some work left. Maybe in the future we will be able to obtain the original words of the Bible and even prove that but presently (according to Bart Ehrman) we cannot be sure.
Regards.
Thank you for taking time to write this all out! I have heard of Bart Ehrman and I have seen a debate between him and David Wallace (I can't remember if it's the link you provided or not) and it was very informative.
In regards to 1 John 5:7-8, David Wallace wrote:
"
Finally, regarding 1 John 5.7–8, virtually no modern translation of the Bible includes the “Trinitarian formula,” since scholars for centuries have recognized it as added later. Only a few very late manuscripts have the verses. One wonders why this passage is even discussed in Ehrman’s book. The only reason seems to be to fuel doubts. The passage made its way into our Bibles through political pressure, appearing for the first time in 1522, even though scholars then and now knew that it was not authentic. The early church did not know of this text, yet the Council of Constantinople in AD 381 explicitly affirmed the Trinity! How could they do this without the benefit of a text that didn’t get into the Greek NT for another millennium? Constantinople’s statement was not written in a vacuum: the early church put into a theological formulation what they got out of the NT.
A distinction needs to be made here: just because a particular verse does not affirm a cherished doctrine does not mean that that doctrine cannot be found in the NT. In this case, anyone with an understanding of the healthy patristic debates over the Godhead knows that the early church arrived at their understanding from an examination of the data in the NT. The Trinitarian formula found in late manuscripts of 1 John 5.7 only summarized what they found; it did not inform their declarations."
Thank you for mentioning that there are non-Trinitarian Christians. Some Muslims (an other non-Christians) assume that Christians all interpret the scriptures the same way. The Christians that believe in the Trinity do not believe in 3 gods, but 1 God who exists in 3 distinct persons (Father, Son, Spirit). I have been meaning to watch a debate between Trinitarian Christians and non-Trinitarian Christians as I would like to see the defense from both sides. I am presently a Trinitarian Christian, but I always ask God for the truth and that may mean I have to change how I believe on something. I have done this in Eschatology and I am very thankful God opened my eyes to the deception that was in most of the Christian teaching on Eschatology today.
Thanks again for your comment!