The Scriptures teach that Jesus’s blood cleanses believers from all sins. Jesus’s blood is the cleansing agent in “the washing of regeneration” (Matt 26:28, Rom 3:25, 5:9; Eph 1:7; Col 1:20; Heb 9:12, 14, 13:12, 20; 1 Pet 1:19; 1 John 1:7; Rev 1:5).
The Bible reveals that the life of flesh is in the blood (Lev 17:11–14; Deut 12:23). The value of the blood of each person is that God made man and woman in His image and gave them life in their lifeblood (Gen 9:4–6; Lev 17:11). God is love and He has made humanity in His image. Therefore, God made people to love (Gen 1:26–27; 1 John 4:8, 16).
Sin is acting contrary to love — to God’s nature — and sin profanes God-given life — eternal life. Sin alienates people from God (Eph 4:18; Col 1:21). Sin is contrary to love and God is love. God’s law reveals when one has sinned and thus died from sinned (Rom 7:7–12; cf. 2:12–16; 4:15). However, all sin and fall short of the glory of God by sinning, and sin earns condemnation and death (Rom 3:23; 5:12; 6:23). Because of our debt of sin, God requires the life of every person and God requires their lifeblood (Gen 9:4–6). This death is separation from God just as death is the separation of the spirit from the body (2 Thess 1:7–9; Jas 2:26). This separation will become eternal unless people reconcile to God through a pure lifeblood and the death of somebody who never sinned.
The Spirit reports of Jesus that “He is the image of the invisible God” (Col 1:15). Jesus was without sin and did not profane the image of God (Heb 4:14–15; 1 Pet 2:22). The Holy Spirit revealed through Paul in Romans 5:8–10,
But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us. Much more then, having now been justified by His blood, we shall be saved from wrath through Him. For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life.
Hebrews 10:22 exhorts, “let us draw near with a true heart in full assurance of faith, having our hearts sprinkled [with blood, v19] from an evil conscience and our bodies washed with pure water.”
What is that pure water? “And now why are you waiting? Arise and be baptized, and wash away your sins, calling on the name of the Lord,” as written in Acts 22:16. In Jesus’s death, water and blood came forth from His side (John 19:34), and when a believer is baptized in Jesus’s name, then that person is baptized into Christ and into His death accessing Christ’s cleansing blood (Rom 6:3–4; cf. 1 John 1:7). Concerning Jesus Christ, John recognized glory and dominion forever “To Him who loved us and washed us from our sins in His own blood” (Rev 1:5).
See more in the article, “The Water and the Blood.”