Question: I just found out that there are lost books of the Bible. Are these considered inspired, and why would God let them become lost?
Well, it is true that there are books and documents that the Bible mentions that have been lost to history, but it is not true that there are lost “books of the Bible”. The Bible, by definition, is the collection of 66 documents (some books, some letters) that we have available to us today. These have never been lost.
But the Bible does mention other documents. Some of these documents are clearly secular. For example, both the book of Esther and Nehemiah mention the “Chronicles of King Xerxes”, the Persian king who enslaved Israel for a period of time (see Esther 2:23; 6:1; 10:2; Neh 12:23). In the New Testament, the apostle Paul quotes from Greek philosophers/poets (Menander in 1 Cor 15:33; and Epimenides in Acts 17:29 & Titus 1:12-13). The point is the Bible sometimes quotes from sources written by non-believers. Certainly these sources were never considered inspired!
Scripture also quotes or makes reference to other documents written by believers, most of which have been lost. Both Jude and 2 Peter quote the “Book of Enoch”. In 1 Corinthians 5:9 Paul refers to his “former letter”. In Colossians 4:16 he mentions a letter he wrote to the believers in Laodicea, and commands it be read to the church in Colossae. Neither letter has been preserved. In the Old Testament, there are several documents mentioned, but I will only list a few: Numbers 21:14 mentions the “Book of the Wars of the Lord”; Joshua 10:12-13 and 2 Sam 1:19-27 mentions the “Book of Jashar” (or, the ‘Book of the Upright’); 1 Kings 14:19 & 16:20 refers to the “Book of the Chronicles of the Kings of Israel” and 1 Kings 14:29 mentions a similar book for the kings of Judah (note: this can’t be referring to 1 & 2 Chronicles, as these were written later). 1 Samuel 10:25 refers to a now-lost document Samuel wrote; 1 Kings 11:41 references the “Acts of Solomon” and 1 Chronicles 27:24 speaks of “The Annals of King David”.
Just because a believer writes something doesn’t make it inspired and part of God’s inerrant word (just go to your local Christian bookstore to confirm this). Not everything Paul wrote was inspired, but everything Paul wrote in the Bible is inspired. The same is true for David, Samuel, Solomon, or any other biblical writer. The overall point is this: God has given us exactly what he wants us to have. He spoke to us through the prophets and apostles, which is the Bible we hold in our hands.