The concept of cleansing in the Bible is deeply rooted in the spiritual and physical purification required by God for His people. This purification is often associated with holiness, as God commands His followers to be holy as He is holy (Leviticus 11:44). The instructions for cleansing are detailed in various parts of the Old and New Testaments, reflecting both ritualistic and moral dimensions.

Old Testament Instructions

1. Ritual Cleansing: The Old Testament provides extensive guidelines for ritual cleansing, particularly in the books of Leviticus and Numbers. These instructions were given to the Israelites to maintain purity and holiness in their community. For instance, Leviticus 14 outlines the cleansing process for a person healed of a skin disease, involving sacrifices and ceremonial washing: "The priest shall order that two live clean birds, cedar wood, scarlet yarn, and hyssop be brought for the one to be cleansed" (Leviticus 14:4).

2. Cleansing from Sin: The Day of Atonement, described in Leviticus 16, was a significant annual event for the Israelites, where the high priest made atonement for the sins of the people. This involved the sacrifice of a goat and the symbolic sending away of another goat, the scapegoat, into the wilderness, representing the removal of sin: "He is to lay both hands on the head of the live goat and confess over it all the iniquities and transgressions of the Israelites" (Leviticus 16:21).

3. Purification after Childbirth: Leviticus 12 provides instructions for purification after childbirth, requiring a woman to undergo a period of purification and to offer sacrifices: "When the days of her purification are complete... she is to bring to the priest at the entrance to the Tent of Meeting a year-old lamb for a burnt offering and a young pigeon or a turtledove for a sin offering" (Leviticus 12:6).

4. Cleansing from Contact with the Dead: Numbers 19 describes the use of the ashes of a red heifer mixed with water for purification from contact with a dead body: "They are to take some of the ashes of the burnt sin offering, put them in a jar, and pour fresh water over them" (Numbers 19:17).

New Testament Instructions

1. Spiritual Cleansing through Christ: The New Testament shifts the focus from ritualistic cleansing to spiritual purification through Jesus Christ. Hebrews 9:13-14 contrasts the Old Testament sacrifices with the cleansing power of Christ's blood: "For if the blood of goats and bulls and the ashes of a heifer sprinkled on those who are ceremonially unclean sanctify them so that their bodies are clean, how much more will the blood of Christ, who through the eternal Spirit offered Himself unblemished to God, cleanse our consciences from dead works to serve the living God?" .

2. Baptism as a Symbol of Cleansing: Baptism is presented as a significant act of spiritual cleansing and identification with Christ's death and resurrection. Acts 22:16 encourages believers to be baptized and wash away their sins: "And now what are you waiting for? Get up, be baptized, and wash your sins away, calling on His name" .

3. Moral and Ethical Cleansing: The New Testament emphasizes the importance of moral purity and ethical living as evidence of spiritual cleansing. James 4:8 calls believers to purify their hearts: "Draw near to God, and He will draw near to you. Cleanse your hands, you sinners, and purify your hearts, you double-minded" .

4. The Role of the Word: Ephesians 5:26 highlights the cleansing power of the Word of God, as Christ sanctifies the church: "to sanctify her, cleansing her by the washing with water through the word" .

The divine instructions for cleansing in the Bible underscore the necessity of both external and internal purity, reflecting God's desire for His people to be set apart and holy. These instructions, while rooted in ancient practices, find their ultimate fulfillment in the redemptive work of Jesus Christ, who provides the means for true spiritual cleansing.