Jesus taught that every part of the Old Testament is inspired and authoritative: the law, the writings, and the Psalms (Lk. 24:44). He taught the men spoken of in the books.  The Old Testament writers were inspired by God to write the Scriptures. According to the Son of God, Moses wrote the books of the law (Lk. 24:44; Jn. 5:45-47); David wrote the Psalms bearing his name (Lk. 20:42); Daniel wrote the book bearing his name (Mt. 24:15).

The Bible inspired by God’s Spirit moving men who were obedient and worshipped him to write. Inspiration does not mean all the words or actions that are recorded in the Bible are inspired-- as if by God made them happen. For example it is recorded in Scripture Peter denied the Lord three times, but God did not inspire his actions or words of denial. Solomon as he was backslidden was musing and caught in worldly philosophy yet he knew the truth and struggled with it. We see a contrast in his statements from his own human reasoning and the wisdom that was from God that was accurate knowledge.

If one does not accept the Old Testament then they cannot believe the words of Jesus, because he referred to it consistently during his ministry. The Apostle Paul wrote, "All scripture is given by inspiration of God…. Not just the red ink portions and not what one feels comfortable with. ALL of it. Jesus said, “The words that I speak unto you, they are spirit, and they are life.”

Jesus quoted the Old Testament(Deut.8:3) in Matt 4:4, "It is written, 'Man shall not live by bread alone, but by every word that proceeds from the mouth of God.'"

Jesus taught that the Old Testament is perfect to the letter (Mt. 5:17-18). It cannot be broken (Jn. 10:35). It is authoritative to every detail. The Greek word translated "broken" in Jn. 10:35 is elsewhere translated "put off" (Acts 7:33) and "loose" (Jn. 11:44). No statement in the Bible can be put off or escaped. All will be proven true. This is the doctrine of inerrancy and infallibility.

Jesus taught that the Old Testament is a book written in advance on the coming of Christ (Lk. 24:44). That the Old Testament characters, events, and miracles are true and historical. Some of the Old Testament people and events Christ referred to are as follows: the creation (Mk. 13:19), Adam and Eve (Mt. 19:4-6; Mk. 10:6-7), Cain and Abel (Mt. 23:35; Lk. 11:50-51), Noah and the flood (Mt. 24:37-39), Abraham (Jn. 8:39-40), the destruction of Sodom and Gomorrah (Lk. 17:28-29), Lot's wife turning to salt (Lk. 17:32), Moses and the burning bush (Mk. 12:26), Jonah and the whale (Mt. 12:39-41; Lk. 11:29-32), Nineveh repenting at Jonah's preaching (Lk. 11:32), The queen of Sheba visiting Solomon (Lk. 11:31).

The New Testament was written within 20-30 years (except Johns epistles and Revelation) of the Jesus death and was written by eyewitness. They prove this by the statement, and authors themselves. There is internal
evidence - Matthew refers to himself as a "tax collector" (Matthew 10:3); John refers to himself indirectly as "the disciple whom Jesus loved" and his rivalries with Peter (John 20:4, 21:20-22).  Luke in the second writing (Acts) alludes to the first epistle, his Gospel; Mark makes an reference to himself (Mark 14:51-52);

Sir William Ramsay, one of the greatest archaeologists who ever lived wrote of Luke the author of the gospel and the book of Acts stating, “Luke is a historian of the first rank; not merely are his statements of fact trustworthy, this author should, be placed along with the very greatest of historians. Luke's history is unsurpassed in respect of its trustworthiness.”

Paul says in 1 Corinthians 15 to ask the eyewitnesses about the resurrection as some of 500 witnesses that saw him all together were still living when he wrote this.

The Bible is called “the word of truth (2 Tim 2:15), Daniel called it “the Scripture of Truth” (Dan.10:21), Prov.30:5 “Every word of God is pure.”

If one does not believe the word, called the Bible then they do not believe the one who is “ the word” nor the one who inspired the word (the Holy Spirit, the Spirit of truth).