In the book of Jude, the author cites the Assumption of Moses and 1 Enoch, two pseudopiographical writings. Critics contest that Jude's citation of these two works is problematic, since neither book is in the orthodox canon and both lack textual witness and historical reliability. In response, one should recognize the inspiration of Jude, Jude's refusal to cite either work as Scripture, and Paul's use of extra-Biblical sources as justification for Jude's citation of the Assumption of Moses and 1 Enoch.
With twenty-five verses, the book of Jude is the third shortest book in the entire Bible; only 2 and 3 John are shorter at thirteen and fourteen verses, respectively. However, any apologist knows that it does not take much to start a controversy, and Jude is no exception. Within those meager twenty-five verses lies a unique conflict that threatens Biblical inerrancy like no other issue could possibly do.
In the book of Jude, two pseudopiographical works, the Assumption of Moses, and 1 Enoch, are cited, the first in verse 9 and the second in verses 14-15. Critics contest that Jude's citing of these two works proves that the Bible is either incomplete, since these two works are missing from the orthodox canon, or in error, since both 1 Enoch and the Assumption of Moses lack textual witness and historical reliability.
The question is, does Jude's citation of these pseudopiographical works prove that the Bible is either incomplete or in error?
This issue is one of the trickier ones in New Testament apologetics simply because it deals with an incredibly unique situation - the citiation of an extra-Biblical work. However, one should not worry that Jude violates any special rule by citing a extra-Biblical source in defense of his thesis. In response to this difficulty, this writer has formulated three points that should defend Jude's use of 1 Enoch and the Assumption of Moses:
(2) Jude cites neither the Assumption of Moses or 1 Enoch as Scripture.
(3) Paul also quotes extra-Biblical sources.
Each point is further examined below:
(1) Inspiration guarantees the truths of Jude 9 and 14-15, whether or not these truths are recorded in any other source
A second option, then, is to assume that Jude believes that this incident really did take place. This does not mean, however, that Jude thinks that the book from which the story is taken is canonical or even totally accurate. It would mean only that Jude believes that this story is true. How would he know that? We must, I think, at this point, fall back on our belief in the inspiration of the Bible. Jude wrote under the direction of the Spirit of God, who led him to this particular passage - and kept him from citing other texts that did not contain true stories.
The conscientious reader will notice that Jude does not quote either book in the traditional New Testament fashion. For instance, when a New Testament writer cites Scripture, usually from the Old Testament, the writer will say something like: "As the Scripture says" (cf. Rom. 3:10). Jude's two citations lack this formula and the Greek word graphe ("Scripture").
(3) Paul quotes extra-Biblical sources
Of course, before one criticizes Jude for quoting pseudopiographical works (if he in fact did so), one must first acknowledge Paul's use of extra-Biblical sources. For instance, Paul, under the guidance of the Holy Spirit, quotes several prominent Greek poets, including Epimenides (Acts 17:28; Titus 1:12), and Menander (1 Cor. 15:33). As John MacArthur notes, "Since Jude was writing under the inspiration of the Holy Spirit...and included material that was accurate and true in its affirmations, he did no differently than Paul." Now, no one would ever assume that the writings of Greek poets are inspired because Paul quoted Greek poets. In short, Paul had a purpose in quoting these poets, just as Jude had a purpose in quoting 1 Enoch and the Assumption of Moses (if he actually quoted them directly).
In conclusion, accusations against Jude's use of 1 Enoch and the Assumption of Moses are unwarranted. For whatever reason, the Holy Spirit determined that a small part of these two works (or at least the events that influenced these two works) would be included in the Holy Scriptures, even if the rest of the works are false. As Christians, we must remember that even extra-Biblical sources can have some truth to them, even if they are not entirely true.
 A pseudopiographical work is one that is ascribed to someone other than its true author. A writer might have many reasons to deliberately work under a name other than his own. For example, some writers would seek to promote an idea by writing under a name of a well-recognized person, while others might look to honor a deceased figure by writing a work in that individual's name using his writing style. See Thomas D. Lea and David Alan Black, The New Testament: Its Background and Message, 2nd ed. (Nashville: Broadman & Holman Publishers, 2003), p. 338.
 The Assumption of Moses apparently records the story of Moses' burial (which is only known by the Lord, cf. Deut. 34:6) and a contention between Michael the Archangel and Satan over Moses' body. Today, this work is preserved only as a fragment. See Henry M. Morris, The New Defender's Study Bible (Nashville: World Publishing, 2005), p. 1978.
 Millard J. Erickson, Christian Theology, 2nd ed. (Grand Rapids: Baker Academic, 1998), p. 225.
 D. A. Carson and Douglas J. Moo, An Introduction to the New Testament, 2nd ed. (Grand Rapids: Zondervan, 2005), p. 694.
 John MacArthur, The MacArthur Bible Commentary (Nashville: Thomas Nelson, 2005), p. 1979.
Carson, D. A., and Douglas J. Moo. An Introduction to the New Testament, 2nd ed. Grand Rapids: Zondervan, 2005.
Moo, Douglas J. 2 Peter, Jude (The NIV Application Commentary). Grand Rapids: Zondervan, 1996.