What is "Manuscript Evidence" and how is it useful?

So how does all of this prove anything? Does it prove the Bible is the Word of God? If not, what's the point?

To be completely honest with you, I do not think it proves the point it seeks to prove. First of all, the fact that there are more New Testament manuscripts than any other book from antiquity only proves that very many people were interested in reading it. Further, what the above table does not state is that the manuscripts listed very frequently do not agree with each other. The variations are not simple typographical errors. They are variations wherein entire words or phrases are different. They also are not variations where an older manuscript has different text than a newer manuscript. Manuscripts produced at roughly the same time seem to be no less prone to disagreeing with each other.

The Nestle-Aland Greek-English New Testament provides on each page a list of alternate versions of each verse, when applicable. As a representative example, we could consider John 1:1-20. According to the apparatus, within this section there is one verse that has 5 different Greek variants, one that has 4 variants, three that have 3 variants, three that have 2 variants, and one that has a single variants: an average of 1.25 variants per verse. If this sample is representative, it is possible that the number of different New Testament texts which could be constructed from all the various manuscripts is on the order of 1 followed by 8,000 zeroes.

The Old Testament is really not any less subject to textual aberrations. A quick survey of the apparatus in The Oxford Jewish Study Bible (2nd ed.) shows that there are around 20 verses in Genesis where the meaning of the original Hebrew is not known. In the Book of Psalms, the editors claim that there are well over 500 such verses.

Finally, even if the manuscripts were perfectly consistent, their meanings - even in the original language - can be distorted. Consider, for example, the passage:

John 5:26–28 (ESV)

26 For as the Father has life in himself, so he has granted the Son also to have life in himself.

27 And he has given him authority to execute judgment, because he is the Son of Man.

28 Do not marvel at this, for an hour is coming when all who are in the tombs will hear his voice

Other translations are similar and seem to be faithful to the Greek Critical Text:

John 5:26–28 (NA27)

26 ὥσπερ γὰρ ὁ πατὴρ ἔχει ζωὴν ἐν ἑαυτῷ, οὕτως καὶ τῷ υἱῷ ἔδωκεν ζωὴν ἔχειν ἐν ἑαυτῷ.

27 καὶ ἐξουσίαν ἔδωκεν αὐτῷ κρίσιν ποιεῖν, ὅτι υἱὸς ἀνθρώπου ἐστίν.

28 μὴ θαυμάζετε τοῦτο, ὅτι ἔρχεται ὥρα ἐν ᾗ πάντες οἱ ἐν τοῖς μνημείοις ἀκούσουσιν τῆς φωνῆς αὐτοῦ

In this case, however, there is an error that has crept into the Critical Text. Since the text in the available manuscripts is unpunctuated, the Nestle-Aland editors need to decide on a punctuation scheme. In this particular case, they chose one that yield the translation:

And he has given him authority to execute judgment,

because he is the Son of Man.

Do not marvel at this,

for an hour is coming when all who are in the tombs will hear his voice

The scheme they chose, however, yields a heretical reading that was recognized and refuted by the Church Fathers. (The King James editors made the same error in interpreting the Byzantine text). The correct reading is:

And he has given him authority to execute judgment also.

That he is the Son of Man,

Do not marvel at this:

for the hour is coming when all who are in the tombs will hear his voice

The alternative Greek reading was used by Paul of Samosata (3rd c.) as support for his argument that Christ was not divine (see, e.g., John Chrysostom's commentary on this passage, also summarized by the Byzantine commentator Theophylact).

Christians, I believe, have to accept the the Bible is the inspired Word of God by faith and not statistics. But I also believe that much discernment is needed in understanding that Word.

"Manuscript Evidence" does not prove that the Bible is God's word - that is a matter of faith. Apologists use manuscript evidence to prove that the Bible has not changed over time; sceptics also use manuscript evidence to prove that the Bible has changed over time. So it takes a very objective person to look at the evidence of the manuscripts and decide between these views on a passage by passage basis.

Scholars have developed a long list of biblical inconsistencies in an attempt to establish which is more likely to be closer to the original, although few believe they can consistently come back to the original. Many of the manuscript versions are grouped under headings such as Western interpolations, Western non-interpolations and so on, which helps establish whether there was a hidden agenda to some possible changes, additions or deletions. Some passages that most critical scholars believe to be interpolations are in almost all modern Bibles (for example Mark 16:9-20), while Wikipedia provides a list of Bible verses not included in modern translations. This is evidence of change, and very probably only represents those changes or potential changes that have come to the notice of scholars.

Using manuscript evidence can be a complex task quite unlike the simplistic notion of merely finding the earliest or most likely extant manuscript. Scholars can read a manuscript verse by verse, even word by word, looking for clues as to the original text. Ronald E. Clements says in 'Israel in its historical and cultural setting', published in his The World of Ancient Israel, page 11, that the Old Testament clearly was composed as the product of a very prolonged literary activity in which few wholly separate and self-contained independent works can be identified. He says the distinction between 'authors' and 'editors' has become increasingly blurred, and in some cases almost meaningless. The prophetic books for example, were clearly not written by prophets, but represent distilled collections of prophetic material, often from diverse ages. History writing also shows every sign of having been a complex work of composition, addition and reinterpretation which, in most cases, can not now be traced back with anything more than a reasonable probability as to its main phases.

Sometimes, scholars look to extra-biblical manuscripts to see whether early Christians knew of a certain, disputed passage from the Bible. For example, Alvar Ellegard suggests in Jesus One Hundred Years Before Christ, page 18-19, the possibility that verses 15:3-8 may be an interpolation that did not exist in the version of 1 Corinthians that Ireneus knew, on the grounds that in trying to contravert the followers of Marcion he could have used the passage but did not.