The Bible is the written Word of God that reveals to us God's purpose for His Creation. In the Old Testament, God makes it clear that mankind is separated from Him by his sin nature, and He appointed one day in the year that addressed the matters for man's sin--the Day of Atonement. On the Day of Atonement, sacrificial blood was shed and taken from the sin offering in the temple, brought by the High Priest into the Most Holy Place, and there the High Priest sprinkled it before the Lord seven times. This atoned for the sins as of that day, but did not atone for our sin nature for which the prophesied Messiah was expected to come to be our atonement. He would come, as the Old Testament prophets predicted, to deliver whoever will receive Him into their hearts the grace of complete forgiveness for our sin nature and life eternal in Christ. This is the New Testament, New Covenant offered by God, the Son of Man, meeting the human need that emanates from our souls seeking identity: "Who am I; why am I here; where am I going."
The Word of God is where we find answers to these needs, speaking to the deepest part of our being. As children of God through having receiving Christ, our old sin nature has died in Christ's shed blood on the Cross, and our new life begins in His resurrection and continues in eternity.