In the first paragraph of Hebrews 9, the author reminds his audience of the Old Testament tabernacle. He uses it as one point of comparison between the Levitical sacrifices and the priestly sacrifice of Christ. The two questions are: 1) who has access to which parts of the tabernacle, and 2) how is each part separated from the others.
The second chapter, then gives us the first half of the comparison: observations from the tabernacle and the Day of Atonement. The high priest may enter the Most Holy Place on the Day of Atonement. The Day of Atonement took place once a year during which time the high priest would make two sin offerings for all of the people. One offering would be burnt on the altar, while the other would be let go into the wilderness. Each of these were metaphors for atonement, substitution, and forgiveness.
The author of Hebrews argues theologically from these metaphors. God is holy as demonstrated by his separation from sinful mankind. In order for God to forgive anyone’s sin, his just wrath must be satisfied. This truth is demonstrated by the requirement of a blood sacrifice. In God’s mercy, God designed the sacrificial system so that a substitute could be offered on behalf of the sinner, to take the punishment due the sinner. By this means, sinners could actually receive forgiveness of their sins.
In this paragraph, the author also points out the weaknesses of this sacrifice. First, since the sacrifice had to be repeated each year, then it could not completely satisfy God’s wrath, and it could not offer complete forgiveness. Secondly, it could not open the way to God—the veil remained a barrier between God and his people. The author completes the comparison in the next paragraph.