One common mistake (if not down-right lie) one hears from many Evangelical apologists is that the text of Isa 53 in the Masoretic Text and the Qumran Text have no textual differences, being one example of the perfect (or near-perfect [99.9% is a figure that Norman Geisler et al., likes to throw out]). However, such is without any basis in reality. Sadly, this “argument” appears in many popular works (e.g., McDowell’s poorly researched book, Evidence that Demands a Verdict). What is even sadder is that many anti-Mormons use this “evidence,” without researching it, to argue against the Latter-day Saint view of the Bible, as summed up in the eighth article of faith (e.g., Ron Rhodes and Marian Bodine, Reasoning from the Scriptures with the Mormons [1995]).
Michael S. Heiser, an Evangelical scholar, presents these differences in a paper entitled, "Letter Differences in Isaiah 52:13-53:12.” One should read it and even save it for future reference, as this claim is very popular, though it is simply false. Hopefully honest Evangelicals who are made aware of this will drop this very errant, if not deceptive, argument.
Another good resource on the issue of textual criticism of the Hebrew Bible, I would recommend the following:
Emanuel Tov, Textual Criticism of the Hebrew Bible (3d ed.: Fortress Press, 2011).