Jesus saith unto them, Have ye understood all these things? They say unto him, Yea, Lord. Then said he unto them, Therefore every scribe which is instructed unto the kingdom of heaven is like unto a man that is an householder, which bringeth forth out of his treasure things new and old.Matthew 13:51-52
The entire Bible is a precious gift given to us by our Heavenly Father. Although it can be a little difficult to understand at times, it is the revealed will of God concerning Himself and mankind. The sixty-six books in the Bible were written by several different men but the Holy Spirit is the Author of it all.
All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:2nd Timothy 3:16
In this parable, Jesus is telling His disciples to preach the kingdom of God as described in both the New and Old Testaments. Throughout the books of the Bible, God has progressively revealed more and more about Himself, His grace, the nature of man, and many other details. We need the entire revelation of God to understand what God would have us to know.
The New Testament is the authority because it gives full explanation of those things spoken of in types and shadows in the Old Testament. However, an understanding of the Old Testament is vital to get the full revelation of God’s character. For instance, the focus on the covenant nature of God in our relationship with Him is much easier to understand if you look at the covenant keeping God of the Old Testament.
The main subject matter of the Bible is the Son of God, Jesus Christ. There is important information about our Redeemer revealed in each one of the books. Jesus Himself told us that is all about Him, therefore we should cherish all of it. That means to read it, study it, sing it, and preach it!
Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.John 5:39