“… to the blood of sprinkling…let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience and our bodies washed with pure water: (Hebrews 12:24, 10:22).
The Old Testament covenant was ratified and inaugurated at Mount Sinai by the sprinkling of blood (Exodus 24:6, 8). In addition, essential to the sacrifices it authorized was the sprinkling of the blood of the sacrificial victim on the altar of sacrifice (Leviticus 1:5, 11; 3:8ff; 9:18).
All of this sprinkling of sacrificial blood was the intentional foreshadowing of the coming Lamb of God and the shedding of His blood which speaks better than Abel’s and is superior to its forerunners.
To avail yourself to the cleansing power of Jesus’ blood and have your evil conscience sprinkled with its atoning ability you must be baptized (Acts 22:16). Your body must be washed so that Christ’s blood can be sprinkled. (You do a similar thing when laundering dirty clothes in the washing machine; the water activates the cleansing properties of the detergent.)
The action of washing the body with water is immersion (baptizo). The action of purifying your conscience with Christ’s blood is sprinkling (rhantismos). Baptism (immersion) saves, not because it removes the filth of the flesh, but because it is a spiritual bath which appeals (NASB; ESV) to God for a good, clear conscience (1 Peter 3:21)–a conscience which is sprinkled with the atoning blood of Christ.
The New Testament’s plan for atonement is a washed body and a sprinkled conscience.