The Lord cleanses. He forgives sin by the shedding of His own blood. So we can pray with the Psalmist David, “Purge me with hyssop, and I shall be clean; wash me, and I shall be whiter than snow” (Ps. 51:7).
Cleansing ceremonies of the Old Testament utilized this hyssop David referenced (see Lev. 14:6, or Num. 19:6). Moses performed a ceremony (see Ex. 24:8) that used hyssop when affirming the Israelites’ covenant with God:
“For when every commandment of the law had been declared by Moses to all the people, he took the blood of calves and goats, with water and scarlet wool and hyssop, and sprinkled both the book itself and all the people, saying, ‘This is the blood of the covenant that God commanded for you.’ And in the same way he sprinkled with the blood both the tent and all the vessels used in worship."
Christ, while hanging on the cross, drank from hyssop (John 19:29). This further associates Him and the spilling of His blood—which led to His marvelous, God-Man entrance into heaven itself for us—with the cleansing ceremonies:
Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins…Christ has entered, not into holy places made with hands, which are copies of the true things, but into heaven itself, now to appear in the presence of God on our behalf.”
Heb. 9:19-22, 24
Christ’s blood—His pure sacrifice—provided cleansing for all believers at once, sanctifying us perfectly. The immediate perfection that comes through Christ because of the cross is called positional sanctification.
While we are imperfect in our actions, we are perfect in Christ, having a position before God of pure, undefiled faultlessness. This truth is expressed in Hebrews 10:14: “For by a single offering, He has perfected for all time those who are being sanctified.” We who are perfect in position before God are also becoming holier; this “becoming” is called progressive sanctification.
So, hyssop and white—our prayer to be cleansed with hyssop and washed white with Christ’s blood is an on-going, submissive prayer to Him. It is a continual request prompted by His desires for us.
God sees those who are pure: “Yet there are some in the church in Sardis who have not soiled their clothes with evil. They will walk with me in white, for they are worthy” (Rev. 3:4). He says they are worthy.
He calls those who wash their robes blessed: “Blessed are those who wash their robes, that they may have the right to the tree of life and may go through the gates into the city” (Rev. 22:14). He welcomes them.
He has adorned those saved for righteous works: “I will rejoice greatly in the Lord, My soul will exult in my God; For He has clothed me with garments of salvation, He has wrapped me with a robe of righteousness, As a bridegroom decks himself with a garland, And as a bride adorns herself with her jewels” (Isa. 61:10). He has clothed them in the garments of salvation—brides in salvation-white adorning themselves with jewels of righteousness.
Our immediate salvation and the increasing holiness of our lives—the two kinds of sanctification—are so intertwined as identifying elements we bear that, though different theological truths, are often used synonymously in Scripture. The robe that Christ gives us is of righteousness; it is perfect and positional through Christ. It cannot be taken away. Yet, it is also progressive, and we participate in it. He saved us to be known as righteous—to be characterized by whiteness—intending us to seek cleansing and purging regularly. This is His desire for us.
When we fight against sin and become discouraged with the continual battle, we can remember that we are already perfect. This dear mercy and complete truth gives us the refreshment in His finished work that we so need in this world. Yet, if we ever discount His desires for righteousness in us, we can remember that He saves those whom He is making righteous. This is how He identifies us as His children, what He watches for in us, what He calls worthy and welcomes; this is the beauty that is our adornment.
The Lord cleanses. The Lord forgives sin. He was sacrificed for us so that, through His blood, judgment stays away forever. We are positionally perfect, and we are progressively becoming perfected—both. Because we are sanctified once and for all, we can pray for increasing sanctification, as David prayed after his murderous act and indulged lust: “Purge me with hyssop, and I shall be clean; wash me, and I shall be whiter than snow” (Ps. 51:7). David connects his increasing sanctification with his one-time sanctification in this verse, as if he is saying: “forgive me of these particular acts and I will be renewed in the knowledge and experience of Your completed forgiveness.”
So, our sorrowful and repentant admission of particular sins in our daily experience draws us into His already-completed forgiveness for all of our sins that happened at the cross. Confession is a beautiful, redemptive part of our regular Christian lives—leading us straight to the crux of what Christ’s sacrifice has done in our hearts.
Later in David’s prayer, we see his confidence in the forgiveness of God, hyssop having swept through his soul: “My sacrifice, O God, is a broken spirit; a broken and contrite heart You, God, will not despise” (Psalm 51:17). Christian, He has forgiven you once and for all at the cross, and He will forgive you again today for what you have done. And He will forgive me. Let’s not stay away from Him; let’s know His forgiveness and be renewed:
Oh Lord, we have sinned. Our sacrifice we pour out to You is of broken, contrite hearts, so sorry and grieved that we have disobeyed. We have forgotten to submit to You, letting ourselves detach from You. We have willfully disobeyed You, abandoning what we knew was right. So, purge us. Let this prayer be as a cleansing ceremony; sprinkle Your shed blood over us. Attend to our souls with hyssop; we remember that You drank bitter judgment for us. Now, our broken sacrifice, oh Lord, You will not despise. We believe in Your forgiveness, won by Christ forever. Now we rest, drinking of Your refreshment; we are renewed in Your perfect sacrifice—the one true sacrifice that the ceremonies of the Old Testament all foreshadowed. You entered not shadow of the tabernacle, but the holiest heaven. Make us more worthy of the Name we bear. Adorn us with righteousness as we re-wrap ourselves in this white garment of salvation given to us through the finished work of Christ. We love You and we worship You. Amen.
 Glaze, Joseph E., Mitchell G. Reddish, and Charles R. Wade. "Hyssop". In Holman Illustrated Bible Dictionary, edited by Chad Brand, Charles Draper, Archie England et al. Nashville, TN: Holman Bible Publishers, 2003.