according to the foreknowledge of God the Father, in sanctification of the Spirit, that you may obey Jesus Christ and be sprinkled in his blood: Grace to you and peace be multiplied.
Probably Peter had Old Testament sprinkling of blood in mind when he wrote this verse. There are many Old Testament allusions in this epistle. Sprinkling with blood in Israel resulted in cleansing (Numbers 19:9), bringing the person sprinkled under the terms and blessings of a covenant (Exodus 24:3-8), and induction into the priesthood and kingship. Members of the priesthood enjoyed the privilege of mediating between God and people (Exodus 29:21; Leviticus 8:30). Members of the royal line in Israel enjoyed the privilege of reigning under God. All of these benefits belong to the Christian whom God has figuratively sprinkled with the blood of Jesus Christ, the final sacrifice for our sins. Obedience is our responsibility, and sprinkling is our privilege. Christ’s blood covers our sins as sinners, cleanses our defilement as unclean people, and consecrates our service as priests and kings.