The answer from God’s word:
“It is merely a historical record of God’s work, and a testimony to the first two stages of God’s work, and you cannot understand the purpose of God’s work from it. Everyone who has read theknows that it is an account of the two stages of work God did during the Age of Law and the Age of Grace. The Old Testament of the Bible records the history of Israel and shows how Jehovah did His work from the creation of the world to the end of the Age of Law. The New Testament records Jesus’ work on earth, which is in the Four Gospels, as well as the work of Paul. Are these not all historical records? … At most, the Bible can teach you a bit about the history of Israel, about the lives of Abraham, David, and Moses and how they revered Jehovah, about how Jehovah burned those who resisted Him and gave instructions to mankind in that era; from the Bible, you can only learn about God’s work in the past. The Bible records how in those days the Israelites revered God and lived their lives under the guidance of Jehovah. Because the Israelites were God’s chosen people, the Old Testament tells of the Israelite people’s loyalty to Jehovah, how all those who submitted to Him were taken care of and blessed by Him. It tells how when God did His work in Israel, He was full of compassion and love, and also possessed of the burning fire, how all the Israelites, from the lowly to the mighty, revered Jehovah, and how the whole nation was thus blessed by God. This is the history of Israel recorded in the Old Testament.”
from “Concerning the Bible (4)” in The Word Appears in the Flesh
“God created the world before He created mankind, but the Book of Genesis was written by Moses during the Age of Law, after humanity was already in existence. Imagine something happened to you today, and you recorded it afterward so that people in the future could read about it. For future generations, this would just be a record of events that happened in a past era, and could only be read as history. The Old Testament, which describes Jehovah’s work in Israel, and the New Testament, which describes Jesus’ work in the Age of Grace, are both records of God’s work in two different eras. The Old Testament records His work in the Age of Law, and so it is a history book. The New Testament is a product of God’s work in the Age of Grace, and when the new work has begun, both testaments are out of date. So the New Testament is also a history book. Of course, the New Testament is not as systematic as the Old and does not record as many things. The Bible contains many things that Jehovah said during the Old Testament, but only some words of Jesus are recorded in the Four Gospels. Naturally, Jesus did much work as well, but it is not recorded in as much detail. The reason that the New Testament records fewer things is that Jesus did less work. The amount of the work that Jesus did on earth during those three and a half years, and the work that the apostles did, is much smaller compared to what Jehovah did. So the New Testament contains fewer books than the Old.
… In Jesus’ day, He led the Jews and all those who followed Him according to the work of the Holy Spirit in Him. He did not look to the Bible for evidence, but spoke as His work dictated. He did not concern Himself with what the Bible said, did not lead His followers down a path found in the Bible. From the very beginning, He preached the way of repentance, and the word ‘repentance’ was not mentioned at all in all the prophecies in the Old Testament. Not only did He not follow the Bible, He brought forth a new path and did a new work. He did not make reference to the Bible when He preached, and the miracles He worked—healing the sick, casting out demons—had never been performed by men during the Age of Law. No one in the Age of Law did the work He did, taught those lessons, had that authority. He simply did His new work, though many people condemned Him, even crucified Him, by using the Bible. His work went beyond the Old Testament; if that had not been the case, why would they have nailed Him to the cross? Was it not because His teachings, His power to cure the sick and cast out demons, had never been recorded in the Old Testament? The work of Jesus was to bring forth a new path; He did not deliberately set out to ‘wage war’ against the Bible or abolish the Old Testament, but simply performed His ministry, bringing the new work to those who thirsted for Him and sought Him out. … Must God’s work obey any rules? Does He need to follow the words of prophets? Which is greater, the Bible or God? Why must God’s work be in line with the Bible? Is it really not within His right to stand above the Bible? Can He not depart from it and do other work? Why did Jesus and His disciples not observe the Sabbath? If He were to observe the Sabbath, to practice the commandments of the Old Testament, then why, after His coming, did He not observe the Sabbath, but washed others’ feet and covered His head, broke bread and drank wine? Were these commandments mentioned in the Old Testament? If Jesus were to adhere to the Old Testament, why did He break these rules? You must know which came first, God, or the Bible? As He is the Lord of the Sabbath, can’t He also be the Lord of the Bible?”
from “Concerning the Bible (1)” in The Word Appears in the Flesh
“Before this, the Israelites read only the Old Testament, which is to say that people in the Age of Grace had only the Old Testament to read. The New Testament did not exist until the Age of Grace; when Jesus was doing His work, there was no New Testament. It was only after His resurrection and ascent to heaven that people began recording His work and the Four Gospels were written, as well as the letters of Paul, the letters of Peter, and the Book of Revelation. Over three hundred years after the Ascension, people collected these writings and assembled them into the New Testament. It was only after Jesus’ work was done that the New Testament came into being, not before. God did much work, and the apostle Paul did much work. Later the letters of Paul and Peter were gathered together into the one book, which concluded with the record of the greatest vision that came to John on the isle of Patmos, because it prophesied the work of the last days. All this was arranged by future generations. … So, how foolish you are, how utterly ignorant, if you worship the Bible as if it were God! Why do you not seek out God’s work today? Only the work of God can save man; the Bible cannot, it has not changed for thousands of years, and if you worship it you will never receive the work of the Holy Spirit.”
from “Concerning the Bible (3)” in The Word Appears in the Flesh