Chapter 9 of Hebrews takes us back and forth between the earthly tabernacle/temple of Israel and the heavenly sanctuary in order to explain the efficacy, finality, and superiority of Christ’s priesthood. Verses 21–22 have explored the truth that the earthly sanctuary had to be regularly purified through the sprinkling of sacrificial blood, setting up today’s passage, which takes us back to the heavenly tabernacle.
Arguing from the lesser to the greater, the author argues that since it was necessary for the earthly tabernacle to be cleansed by the blood of animal sacrifices, it is necessary for the heavenly tabernacle to be purified by a superior sacrifice (v. 23). This might sound a little strange to us, for since God dwells in heaven in “unapproachable light” (1 Tim. 6:16), heaven and its sanctuary do not have any defilement from sin that needs cleansing. However, the author is simply speaking in a general way here in order to affirm the greatness of Jesus’ work. The various cleansings and purifications performed in the earthly tabernacle had different purposes, and there is not necessarily an exact parallel to everything that Christ has done in the heavenly temple. Furthermore, a lot of the purification and sanctification language used in Scripture has to do with setting something apart for a holy use, so it is likely that this is largely what the author has in mind in Hebrews 9:23.
In entering the heavenly tabernacle, we see in verse 24, Jesus entered the presence of God Himself. Our Creator did manifest His presence in the earthly sanctuary in the Most Holy Place (Ex. 25:22), but even then it was a mediated presence wherein the Lord had to veil Himself to some degree from the Levitical high priest lest the high priest see Him directly and die (33:20). But Christ the God-man entered the direct presence of our Maker upon His ascension, being perfectly sinless and even very God of very God as well as very man of very man.
Hebrews 9:25 says that unlike the old covenant high priests who had to make annual sacrifices to enter the Most Holy Place on the Day of Atonement (Lev. 16), Jesus had to offer Himself only once to secure access to the heavenly Most Holy Place. This reveals the superiority of Jesus’ work. His death took Him into the heavenly Most Holy Place forever. This was the high point of human history, when Christ inaugurated His kingdom (Heb. 9:26).