The grass withereth, the flower fadeth, but the word of our God shall stand for ever. (Isa 40:8)
For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. (Matt 5:18)
Heaven and earth shall pass away, but my words shall not pass away. (Matt 24:35; cf. Mark 13:31; Luke 21:33)
It is common for some Protestants, especially those from Fundamentalist camps, to reference such verses in favour of the perfect preservation of the Bible. Furthermore, some have used such texts in support for the formal sufficiency of the Bible (see my book, Not by Scripture Alone: A Latter-day Saint Refutation of Sola Scriptura for more on this doctrine).
Perhaps it should be enough to note that, when Isaiah wrote his book, and when Jesus uttered those words in the Gospel of Matthew, when Jesus uttered those words, much of the Old and none of the New Testament had not yet been inscripturated so the "Bible"could not have been in view here. Secondly, The "word[s] [of God]" are not limited to the written word, and neither are other texts (e.g., Isa 40:8) or other similar. As a Reformed Protestant apologist writing in defense of Sola Scriptura admitted:
[T]here is a difference between the Word of God, which is eternal (Psalm 119:89, 152, 160), and the Bible, which is not. The Bible is the Word of God written. If one were to destroy one paper Bible, or all paper Bibles, he would not have destroyed the eternal Word of God. One such example is given in Jeremiah 36. The prophet was told by God to write His words in a book, and to read it to the people. Wicked king Jehoiakim, not comfortable with what had been written, had the written Word destroyed. God then told the prophet to write the Word down again. The king had destroyed the written Word, but he had not destroyed God's Word. God's Word is eternal propositions that find expression in written statements. (W. Gary Crampton, By Scripture Alone: The Sufficiency of Scripture [Unicoi, Tenn.: The Trinity Foundation, 2002], 156)
Furthermore, absolutizing such texts in the way that many (not all, to be fair) Protestants are wont to do will result in one having to ignore textual criticism, as such an (eisegetical) interpretation would mean there would be no textual variations whatsoever. However, such is simply false. Commenting on some of the difficulties posed to texual criticism, and how this approach is detached from reality, three conservative Protestant scholars noted:
Even with all of this help [from textual criticism], Christians often ask two important questions or which there are no simple answers. First, why did God in his providence not insure that an inerrant, inspired original was also inerrantly preserved? Second, how do we as Christians deal with those portions of traditional translations (like the KJV) that modern discoveries have shown were not part of the original autographs? The first question takes on added significance in light of other religions that claim, however erroneously, that their sacred writings have been perfectly preserved (most notably the Book of Mormon and the Qur’an/Koran). To be sure, we do not know God’s hidden motives. Perhaps he did not want us to idolize a book but to worship the God who became incarnate in Jesus. Leaving the transmission of Scriptures to fallible human beings parallels leaving the proclamation of those Scriptures to sinful and potentially rebellious disciples. God does not choose to override free will in either case, and he reveals and inspires only at particular moments in human history. But there is a sense in which we can discern his providence in the amazing extent to which the texts have been preserved.
The second question becomes particularly acute with regard to the two longest passages (printed in most Bibles) that almost certainly did not appear in the original manuscripts: Mk 16:9-20 (an additional account of Jesus’ resurrection) and Jn 7:53-8:11 (the story of the woman caught in adultery). The necessary approach should be clear—whatever was most likely in the original texts should be accepted as inspired and normative; what was not in those texts should not be given equal status. But application proves more difficult. As noted elsewhere in this book, Jn 7:53-8:11 may be a true story, from which we can derive accurate information about Jesus’ view of the Law, even if it did not original form part of John’s Gospel. On the other hand, there is almost no evidence to support Jesus having said, “He that believes and is baptized shall be saved” (Mk 16:16), as if baptism were necessary for salvation, or for the promise that believers may pick up snakes, drink their venom, and yet not be harmed (Mk 16:18). One unnecessarily risks suicide by treating that text as normative! But in both Mark and John, the textual evidence is very strong for rejecting these passages as inspired Scripture.
Or what about verses in which the NT quotes the OT but follows the Septuagint, even though the meaning in the Greek translation does not accurately reflect the Hebrew of traditional OT manuscripts? These differences prove more difficult to assess. The traditional Hebrew versions, known as the Masoretic text (MT), date from no earlier than the A.D. 800-900s. The existing Septuagint (LXX) manuscripts go back an additional half a millennium or more. It is possible, therefore, that at times the LXX accurately translated a Hebrew original that later became corrupted. Portions of OT books found among the Dead Sea Scrolls (DSS) from as long ago as 200 B.C. have suggested that occasionally though not often, this was exactly what happened. Compare, for example, Heb 1:6, which quotes a longer form of Deut 32:43 found only in the LXX and DSS.
Aramaic Targums, which combined free translation with occasional explanatory additions and commentary, may at times also reflect an older text. Interpreters, for example, have often wondered how to account for the end of Eph 4:8, “he gave gifts to men,” when the Hebrew of Psa 68:18 that Paul is quoting reads “you received gifts from men.” But at least one early Targum contains an Aramaic equivalent for Paul’s word, so it is possible than its author reflected the intent of the original Hebrew. (William W. Klein, Craig L. Blomberg, and Robert L. Hubbard, Jr. Introduction to Biblical Interpretation [Dallas: Word Publishing, 1993], 72-3, comment in square bracket added, italics in original)
Do note that the Book of Mormon itself, nor informed Latter-day Saints, claim, as the authors errantly wrote in the above, claim that it is “perfectly preserved” as Muslims claim about the Qur’an. LDS have discussed in great detail textual changes in the manuscripts and printings of the text, such as Royal Skousen’s 6-volume Analysis of Textual Variants of the Book of Mormon. Furthermore, I do believe a good case can be made, in light of recent scholarship, that Mark 16:9-20 is original (see Nicholas P. Lunn, The Original Ending of Mark: A New Case for the Authenticity of Mark 16:9-20 [Pickwick, 2014]). Notwithstanding, the questions and cautions the authors raise should be taken by all Bible readers seriously (not just Evangelicals, but my fellow Latter-day Saints and others).