"And the LORD spake unto Moses, saying, This shall be the law of the leper in the day of his cleansing: He shall be brought unto the priest: And the priest shall go forth out of the camp; and the priest shall look, and, behold, if the plague of leprosy be healed in the leper; Then shall the priest command to take for him that is to be cleansed two birds alive and clean, and cedar wood, and scarlet, and hyssop: And the priest shall command that one of the birds be killed in an earthen vessel over running water: As for the living bird, he shall take it, and the cedar wood, and the scarlet, and the hyssop, and shall dip them and the living bird in the blood of the bird that was killed over the running water: And he shall sprinkle upon him that is to be cleansed from the leprosy seven times, and shall pronounce him clean, and shall let the living bird loose into the open field." Leviticus 14:1-7
The cedar wood represents the cross of Calvary which was put upon Christ against His will.
The scarlet represents the robe that was put upon Christ during the crucifixion. "And they stripped him, and put on him a scarlet robe." Matthew 27:28
The hyssop represents the hyssop that was put to Christ's mouth during the crucifixion. "Now there was set a vessel full of vinegar: and they filled a spunge with vinegar, and put it upon hyssop, and put it to his mouth." John 19:29
The bird that was killed over the running water represents Christ dying on the cross, and when the soldier pierced His side, water, and blood came gushing out. It is written: "This is he that came by water and blood, even Jesus Christ; not by water only, but by water and blood. And it is the Spirit that beareth witness, because the Spirit is truth." 1 John 5:6
Just as Christ came by water and blood, He is also the Word and the Holy Ghost. It is written in the following verse: "For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one." 1 John 5:7
The bird that is loosed into the open field represents believers who are cleansed by the blood of Christ.
The plague of leprosy represents our sin.