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 to 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, yet the Exodus account (referenced above) has Moses sprinkling the altar, and the people.
However, there is no contradiction here, for the altar and the testament (the words of the covenant) were considered as one.
For where a testament 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 first testament, the Law, was dedicated by the blood of sacrificial animals, therefore the altar on which those sacrifices were slain, is one, with the words of the covenant which was confirmed by the blood of those sacrifices.
The altar on which Christ was slain, the cross, is one with the words of the New Testament established by his blood: For this is my blood of the new testament, which is shed for many for the remission of sins. ~ Matthew 26:28
The writer of Hebrews tells us that when Moses had sprinkled the blood of animals by which the first covenant was ratified, he said, This is the blood of the testament which God hath enjoined unto you. ~ Hebrews 9:20
Likewise, the blood of Jesus is the blood of the testament, by which God has joined himself to those who follow Jesus, and the words of the New Testament are forever established by the blood of Jesus.
Now consider for a moment another example of the sprinkling of blood in scripture: When the priests were consecrated for service to the Lord, the blood was sprinkled on the altar, and on the priests, and on their priestly garments. ~ See Exodus 29:16, 20-21
Of particular importance is that 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 (a type of the Holy Spirit) were united as one in sanctifying the priests and their garments as holy to the Lord.
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 made holy by the sprinkling of the blood and the anointing oil, we who believe in Jesus are made holy (as a priesthood) by the sanctifying work of the 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 and that we should be obedient to the holy calling to be holy even as HE IS HOLY!