During the time of the Exodus, the people of Israel heard a message of good news from Moses (Hebrews 4:2). It consisted of redemption from slavery, the Passover, baptism in the Red Sea, and a journey through the wilderness to the Promised Land. The good news, then, included the occurrences of and the knowledge about all the steps along the way, all of the benchmarks. The purpose for which all those events occurred was the most important part. What good was it to have the death angel pass over their house, for them to receive the forgiveness of sin and redemption from slavery, if they never made it to the Promised Land? That is Paul's warning. The steps, though vital in themselves, are not as important as the goal.
This warning applies especially to today. What Jesus Christ did in His life, in His death and in His resurrection, is awesome, a wonderful and great gift. It is good news that these things have occurred, but they are not the good news. The good news is the goal, and that has not yet occurred. What Jesus Christ did is exceedingly important to the fulfillment of God's purpose, but it's still possible for us to reject the Son of God even after we have accepted His blood for the forgiveness of our sins, as Hebrews 12 also shows very clearly. So in this analogy, life in, possession of and governance of the Promised Land was the culmination, the good news, the fulfillment—at least physically—of the promises to Abraham.
The message that Jesus Christ brought, the gospel, is about the Kingdom of God, the culmination, the goal, the fulfillment. Certainly it includes the knowledge of and information about those benchmarks along the way, but the Kingdom of God is the goal toward which every Christian is aiming.
These doctrines or principles are very important, as Hebrews 6:1 shows. God will grant us repentance and forgive us through the blood of Jesus Christ. What good news! But it is not the good news. That is the principle: Being granted repentance and having faith in and through Jesus Christ are good news, but the result of those things is the real good news. It is the culmination of the process—"let us go on to perfection"—that is the good news.
What if the gospel concentrates solely on the person of the Messenger and overlooks the message He brought? If it focuses on the greatness of the Messenger, all of the good news about Him, and His importance to the process, His significance actually begins to diminish. If one concentrates on the Messenger, he will believe that salvation comes merely because he believes in the Messenger (see Matthew 7:21). Further development of that human being stops because he has made the wrong choice. That is the problem with concentrating on the Messenger, as important as He is.
The gospel does not specifically concentrate on Christ, yet we do not want to denigrate the major role He plays either. The process pivots around Him, though its ultimate purpose will end when He delivers the Kingdom to the Father (I Corinthians 15:24). The Messenger became the High Priest, and we are saved through His life. Christianity has to go beyond the fact that He was the Messenger. Now He is the High Priest in heaven. And though He is High Priest, we still have choices to make in relation to the Kingdom of God.
That is why Hebrews 6:1 says, "Therefore, leaving the discussion of the elementary principles of Christ, let us go on to perfection." As we go through the process that the Messenger went through and begin to experience what He accomplished, He is magnified in our eyes, because we try to do what He did and realize how awesome and difficult what He did was. While we try to imitate Him, the process of creation is going on. If we stop trying to imitate Him, He becomes diminished. That is why we have to go on to perfection, to completion, because the process is not complete with just believing in Jesus Christ.