From the commentary on the psalms by Saint John Fisher, bishop and martyr
If anyone has sinned, we have an advocate with the Father
Our high priest is Christ Jesus, our sacrifice is his precious body which he immolated on the altar of the cross for the salvation of all men.
The blood that was poured out for our redemption was not that of goats and calves (as in the old law) but that of the most innocent lamb, Christ Jesus our Savior.
The temple in which our high priest offered sacrifice was not one made by hands but built by the power of God alone. For he shed his blood in the sight of the world, a temple fashioned by the hand of God alone.
This temple, however, has two parts. The first is the earth, which we now inhabit. The second is as yet unknown to us mortals.
Christ first offered sacrifice here on earth, when he underwent his most bitter death. Then, clothed in the new garment of immortality, with his own blood he entered into the holy of holies, that is, into heaven. There he also displayed before the throne of the heavenly Father that blood of immeasurable price which he had poured out seven times on behalf of all men subject to sin.
This sacrifice is so pleasing and acceptable to God that as soon as he has seen it he must immediately have pity on us and extend clemency to all who are truly repentant.
Moreover, it is eternal. It is offered not only each year (as with the Jews) but also each day for our consolation, and indeed at every hour and moment as well, so that we may have the strongest reason for comfort. That is why the Apostle adds: He has secured an eternal redemption.
All who have embarked on true contrition and penance for the sins they have committed, and are firmly resolved not to commit sins again for the future but to persevere constantly in that pursuit of virtues which they have now begun, all these become sharers in this holy and eternal sacrifice.
Saint John sets this before us in these words: My little children, I am writing this to you so that you may not sin. But if anyone does sin we have an advocate with the Father, Jesus Christ the righteous one. And he is the propitiation for our sins, and not only for our sins but also for those of the whole world.