Through my entire life, I have heard certain similes and metaphors that are used to explain the spiritual interpretation of Old Testament passages.
Ironically, those who hold to an extreme view of Sola Scriptura fail to recognize that many of their allegorical typology are mostly based upon the Apostolic teachings passed down to us through the second generation of disciples.
In Christian typology the two birds in Leviticus 14:49-53 represent Christ. The scarlet yarn, the cedarwood and the hyssop of the sacrifice represented Christ. (Leviticus 14:1-7) And Leprosy represented sin. The Scapegoat of Leviticus 16:10 represented Christ carrying away our sin.
None of these similes were invented by your Pastor. Their commentaries tell them the similes, but not the source. In a disciplic movement, the source of a teaching is important. Plus keeping in mind from whom the teaching descends, we can learn about the context in which such teachings were shared and what we must do in order to conform to them today and become true disciples of Jesus Christ.
The following is an excerpt from Manuscript of writings of Justin.
By the two birds Christ is denoted, both dead as man, and living as God. He is likened to a bird, because He is understood and declared to be from above, and from heaven. And the living bird, having been dipped in the blood of the dead one, was afterwards let go. For the living and divine Word was in the crucified and dead temple [of the body], as being a partaker of the passion, and yet impassible to God.
By that which took place in the running water, in which the wood and the hyssop and the scarlet were dipped, is set forth the bloody passion of Christ on the cross for the salvation of those who are sprinkled with the Spirit, and the water, and the blood. Wherefore the material for purification was not provided chiefly with reference to leprosy, but with regard to the forgiveness of sins, that both leprosy might be understood to be an emblem of sin, and the things which were sacrificed an emblem of Him who was to be sacrificed for sins.
For this reason, consequently, he ordered that the scarlet should be dipped at the same time in the water, thus predicting that the flesh should no longer possess its natural [evil] properties. For this reason, also, were there the two birds, the one being sacrificed in the water, and the other dipped both in the blood and in the water and then sent away, just as is narrated also respecting the goats.
The goat that was sent away presented a type of Him who taketh away the sins of men. But the two contained a representation of the one economy of God incarnate. For He was wounded for our transgressions, and He bare the sins of many, and He was delivered for our iniquities.
And because Christianity is a disciplic movement, you can rest assured, that these similes are part of Christ’s own oral teaching, passed down through the disciples of two-thousand centuries.