In these passages Paul contrasts living according to the Law of Moses to living according to Faith in Jesus Christ. Paul points out that before Faith came, all Jews were ‘kept in custody’ under the Law. However, the Law served its purpose in leading people to Jesus Christ.
The Law contained an elaborate process of sacrificing animals to atone for sins. This process pointed toward Jesus Christ, who God sacrificed for the sins of mankind. Our Faith in Jesus Christ enables us to be covered by Jesus’ shed blood on a Roman cross.
Once we are covered by Jesus’ blood, God sees us as His offspring. God sends forth His Spirit into us, so that we may see God as our Father in Heaven and get to know Him.
The Bible defines Eternal Life as knowing God and Jesus Christ. There is only one way to get to know God and Jesus: Read the Bible. For our belief to have any meaning at all, we must first accurately characterize Jesus.
Jesus is characterized only in the Bible. Therefore we must read the Bible in order to understand who He is. Only then can we know how to believe in Him. The Bible says that believing in Jesus is essential to our gaining entry into Heaven after we die.