Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied. ~ Peter 1:2
Throughout the Old Testament, the sprinkling of the sacrificial blood had to do with that which was consecrated as holy to the Lord. For example, when God made covenant with the children of Israel, Moses sprinkled the blood of the covenant to ratify the covenant and consecrate the people to the Lord.
And Moses took half of the blood, and put it in basons; and half of the blood he sprinkled on the altar. And he took the book of the covenant, and read in the audience of the people: and they said, All that the Lord hath said will we do, and be obedient. And Moses took the blood, and sprinkled it on the people, and said, Behold the blood of the covenant, which the Lord hath made with you concerning all these words. ~ Exodus 24:6-8
The author of Hebrews tells us tells us that Moses sprinkled both the book of the covenant and all the people ~ Hebrews 9:19. The Exodus account has Moses sprinkling the altar, and the people.
In this we can see a correlation between the covenant, and the altar by which the covenant was ratified.
For where a testament (covenant) is, there must also of necessity be the death of the testator. For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth. Whereupon neither the first testament was dedicated without blood. ~ Hebrews 9:16-18
The altar by which Israel (under the Law) was covenanted to God, was dedicated with the blood of sacrificial animals, and could only serve as a foreshadowing of something much greater: the sacrifice of Jesus.
But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises. For if that first covenant had been faultless, then should no place have been sought for the second. ~ Hebrews 8:6-7
The more excellent ministry which Jesus has obtained is High Priest in the Heavens in contrast to the priests who served under the law. The priests under the law were imperfect men who could only offer animal sacrifices which could never take away sins. Jesus, however, is perfect, and his precious blood cleanses from all sin.
The altar on which Christ was slain, the cross, has the power to sanctify and make us holy in the sight of God because of the life of Jesus which was sacrificed on it. The life and grace of Jesus is the spirit of the New Covenant! Unlike the first Covenant, the sacrifice which was slain on the altar of the New Covenant, lives! He lives in the presence of God to make intercession for us.
Whereas the Old covenant was ratified with the blood of dead animals, and had to constantly be renewed, and had no power to give life, the New Covenant was ratified by the blood of crucified Christ who has risen from the dead!
The first covenant served only as a type and shadow of Christ. Under it the priests were consecrated for service by the sprinkled blood upon the altar, the sprinkling of blood upon themselves, and the sprinkling of blood on their priestly garments. ~ See Exodus 29:16, 20-21
The anointing oil (a type of the Holy Spirit) was sprinkled with the blood to consecrate the priests.
And thou shalt take of the blood that is upon the altar, and of the anointing oil, and sprinkle it upon Aaron, and upon his garments, and upon his sons, and upon the garments of his sons with him: and he shall be hallowed, and his garments, and his sons, and his sons’ garments with him. ~ Exodus 29:21
The blood and the anointing oil were united in sanctifying the priests and their garments as holy to the Lord. This was a foreshadowing of the consecration of God’s people through the blood and Spirit of Jesus Christ.
The apostle Peter, who begins his epistle by uniting sanctification of the Spirit with obedience and the sprinkling of the blood of Jesus Christ, also tells us that we are holy priesthood and a royal priesthood, who offer spiritual sacrifices to God through Jesus Christ.
As the priest were set apart for service to the Lord (under the type) by the sprinkling of the blood and the anointing oil, we who believe in Jesus are made holy as a spiritual priesthood in the New Covenant by the sanctifying work of the Holy Spirit and the sprinkling of the blood of Christ.
13 Wherefore gird up the loins of your mind, be sober, and hope to the end for the grace that is to be brought unto you at the revelation of Jesus Christ;
14 As obedient children, not fashioning yourselves according to the former lusts in your ignorance:
15 But as he which hath called you is holy, so be ye holy in all manner of conversation;
16 Because it is written, be ye holy; for I am holy.
17 And if ye call on the Father, who without respect of persons judgeth according to every man’s work, pass the time of your sojourning here in fear (the fear of the Lord):
18 Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers;
19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
20 Who verily was foreordained before the foundation of the world, but was manifest in these last times for you,
21 Who by him do believe in God, that raised him up from the dead, and gave him glory; that your faith and hope might be in God.
22 Seeing that you have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently:
23 Being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth for ever. ~ 1 Peter 1:13-23
The context to which the words, “the precious blood of Christ” belong, is that of sanctification for a holy life. God redeemed us with the precious blood of Christ, so that he could sanctify us by his Spirit, that we should be obedient to the holy calling he has given to be holy even as HE IS HOLY!