In these passages, the writer speaks of Jesus being our High Priest. Jesus is our advocate before God. We have access to God the Father through Jesus who speaks to God for us. The Jewish priests of the old testament represented the people before God and sacrificed animals to atone for the peoples’ sins.
Jesus now represents His followers before God, but He doesn’t sacrifice animals for our sins. Jesus was the sacrifice for our sins. His atoning death on the cross was the ultimate sacrifice for the sins of mankind. No further sacrifices are necessary to atone for our sins. Our sins have been removed so that we can be with God the Father in His Kingdom one day. However, this is conditional. It is conditional on our belief and trust in Jesus Christ, which will be evidenced by the life we live and the choices we make. Jesus will be our advocate before God if we are one of His followers. He will not be an advocate for those who do not believe or those who are given over to their sins.
The Bible says that when we believe in Jesus Christ we are given Eternal Life which yields many blessings for the believer. However, we will always have free will to choose what we believe. Some have believed in Jesus and then fallen away or departed from their belief. These people no longer have with the Bible calls Eternal Life. And if they die in their unbelief, the Bible says that they will spend eternity in Hell. So, if you choose to believe in Jesus, don’t ever turn back.