The leper that was to be cleansed had to bring a log of oil as one of his offerings. It was from this oil that the altar was sprinkled and the leper anointed. The offering became the anointing. Now, if we see in this oil the Holy Spirit, this may seem confusing. How could one “offer up” the Holy Spirit? And having offered it up, how could one then anoint with it? Strange as this might seem, it is exactly what the Lord Jesus did.
Like the scapegoat on the Day of Atonement, these two birds represent one sacrifice, but since they couldn’t kill a bird and bring it back to life again, two birds had to be used. One died as a result of sin; the other was set free, representing the liberty we have when our sins have been washed away.