All sixty-six books of the Bible were inspired of God. 2 Timothy 3:16 says, "All scripture is given by the inspiration of God." God has given us everything we need. 2 Peter 1:3 says, "His divine power has given us all things that pertain to life and godliness." God has told us everything we need so we can please Him and go to heaven.
Inspiration means "God breathed". God prompted and controlled the writing of the Bible. When did God do this? Hebrews 1:1-2 says, "God who at various times and in various ways spoke in times past to the Fathers by the prophets, has in these last days spoken to us by His Son." God in Old Testament times spoke to the people through the prophets as we read in 2 Peter 1:21, "For prophecy never came by the will of man, but holy men of God spoke at they were moved by the Holy Spirit." The word of God did not come from the will of man but God spoke to man through the prophets. Man’s will did not enter into God’s word. 1 Corinthians 2:13 says, "These things we also speak, not in words which man’s wisdom teaches, but which the Holy Spirit teaches."
How did God accomplish the inspiration of His word in the New Testament? As Jesus told His apostles in John 14:26 & 16:13, "The Holy Spirit whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you…when He the Spirit of truth is come, He will guide you into all truth." The Holy Spirit would be guiding them so they could teach all the truth of God’s word.
Just as God used miracles in the Old Testament to confirm that the word being taught was from Him, He confirmed His word in New Testament times, "God also bearing them witness both with signs and wonders, with various miracles, and gifts of the Holy Spirit (Hebrews 2:3). Because the Bible is the pure and inspired word of God it "is able to save your souls" (James 1:21).