"And having an high priest over the house of God;" (Hebrews 10: 21)
Jesus is our high priest today.
In fact, He ministers on our behalf, and ever stops serving:
"For even the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many." (Mark 10: 45)
"Who is made, not after the law of a carnal commandment, but after the power of an endless life." (Hebrews 7: 16)
Why is it important for us to know that our High Priest today has an endless life?
Under the Old Covenant, the high priest would go into the Holy of Holies once every year to atone for the sins of the people:
" And Aaron shall make atonement upon its horns once a year with the blood of the sin offering of atonement; once a year he shall make atonement upon it throughout your generations. It is most holy to the LORD.” (Exodus 30: 11)
This high priest would enter once a year, which signified that the shedding of blood was not enough.
When Jesus shed His blood, the eternal value of His blood covers our sins forever.
Not only that, but because He is a perfect, never-dying priest, we can rest assured that our perfect standing before God will never change.
"For I am the LORD, I change not; therefore ye sons of Jacob are not consumed." (Malachi 3: 6)
We are made not just righteous before God, but the righteousness of God in Christ (2 Corinthians 5: 21), and we keep receiving this righteousness (Romans 5: 17) because our righteousness is based on Jesus, our High Priest forever after the order of Melchizedek (King of Righteousness):
"(For those priests were made without an oath; but this with an oath by him that said unto him, The Lord sware and will not repent, Thou art a priest for ever after the order of Melchisedec:)" (Hebrews 7: 21)
When we understand whose we are, and where we are in (in Christ), then we understand fully who we are:
"Herein is love perfected among us, that we may have boldness in the day of judgement; because as He is, so are we in this world." (1 John 4: 17)