“For I am the LORD who brought you up out of the land of Egypt to be your God. You shall therefore be holy, for I am holy.” (Leviticus 11:45 ESV)
Here’s the big picture: God wants us to approach him and to know him. But God is holy, and our sin is serious. Forgiveness and cleansing is costly. And it involves death. All of this points ahead to the person and work of Jesus Christ, who is “the Lamb of God, who takes away the sin of the world” (John 1:29).
Washed and set free (Lev. 14:1-7). Here’s what a little bird teaches us: the principle of substitution — one dies, one goes free. The one who lives is dipped in the cleansing water / blood of the one who died. Perhaps the cedar wood points ahead to the Cross. The bird “washed in the water and blood” goes free. Though it may have been puzzling to the people at that time, this seems to be a clear picture of Christ’s death and its cleansing power.
Which way holiness runs. Notice in these chapters of Leviticus… in which direction holiness and cleanliness run. Notice the context of treating bodily discharges and leprosy, as well as sin. If something designated “holy” touches something “common”, the holy thing becomes unholy (or common). If something designated “clean” touches something “unclean”, the clean becomes unclean rather than the unclean becoming clean. There were two exceptions: the holy anointing oil and the altar of sacrifice.
In those cases, the holy made holy whatever it touches, and the power of God “reverses the flow”, so to speak. To the Jewish observers of Jesus’ miracles, then, this would make his works even more stunning. Normally, a person who touched a leper, or who was touched by a bleeding person (see Matt. 8:2-3; 9:20-22) would become unclean. Yet in Jesus’ case it is totally reversed — the unclean person becomes clean.
There is power in Jesus — the Anointed One, the sacrificial Lamb — to reverse our human condition, to make the unclean clean and the unholy holy. That is why every believer who embraces Christ by faith becomes clean and holy. Hence even the poorest sinner is a “saint” (or, holy one). Our sin does not defile Christ; his holiness makes us holy.
The NT book of Hebrews is the companion to the OT book of Leviticus. Here is one application: “For if the blood of goats and bulls, and the sprinkling of defiled persons with the ashes of a heifer, sanctify for the purification of the flesh, how much more will the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify our conscience from dead works to serve the living God.” (Hebrews 9:13-14 ESV)