"Day after day every priest stands and performs his religious duties; again and again he offers the same sacrifices, which can never take away sins. But when this priest had offered for all time one sacrifice for sins, he sat down at the right hand of God. Since that time he waits for his enemies to be made his footstool, because by one sacrifice he has made perfect forever those who are being made holy." NIV translation
Unlike the other priests, Jesus offered himself once and for all and then He went and sat down at the right hand of God. In the temple, there were no chairs as the priests were constantly offering sacrifices. What does "his enemies" mean? An enemy of Christ and of God is one who denies the sufficiency of His sacrifice. Those who accept His sacrifice have been made perfect in the sight of God. Every sin that we have or will commit was paid for when Jesus went to the cross on our behalf. As Christians, we may not look perfect to those around us but, in the sight of God, we are and we are being made holy (set apart for His use).
"The Holy Spirit also testifies to us about this. First he says: 'This is the covenant I will make with them after that time, says the Lord. I will put my laws in their hearts, and I will write them on their minds.' Then he adds: 'Their sins and lawless acts I will remember no more.' And where these have been forgiven, there is no longer any sacrifice for sin." NIV translation
As Christians, we do not need a religious leader to tell us what is right and wrong. As we see here, the laws of God are written on our hearts and mind by Him. We also see that our sins have been forgiven and we must remember that, when God forgives, it is like the sin never even happened.
As people, we like to forgive but keep the memory of the wrong in the back of our minds but, when God forgives, then it is also forgotten. Do you have someone in your life that always tries to bring up your past sins? If so, you can tell them that, in God's eyes, it is like they never even happened. Then, ask them if they think they are above God.
"Therefore, brothers, since we have confidence to enter the Most Holy Place by the blood of Jesus, by a new and living way opened for us through the curtain, that is, his body, and since we have a great high priest over the house of God, let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water." NIV translation
Since we have this new covenant in the blood of Jesus, we are made righteous and we can enter the very presence of God. In fact, God now lives in us through the Holy Spirit. We are still people who mess up and so we have Jesus as our high priest who intervenes on our behalf with the Father. The old high priests and sacrifices could not cleanse the conscience but Christ has cleansed us completely and so we can walk in complete assurance of our relationship with God.