The "for" is explanatory. Verses 24-28 explain verse 23. "Sanctuary" here is the Old Testament tabernacle. "Copy" could be translated "type." The earthly is the counterpart of the heavenly, not vice versa. Heaven itself is prefigured. Jesus did not even enter a sanctuary. Again "for us" denotes the vicarious and substitutionary nature of Christ's sacrifice, "in our stead." The High Priest appeared in the Most Holy Place for a few moments once a year. Christ entered the very presence of God in our stead permanently and forever.
Westcott: In the Old Testament the thought of 'the face'(Hebrew panim) of God occupies an important place, as expressing the revelation of His Presence (Exodus 33:14; Deuteronomy 4:27). The significance of the phrase is seen specially in the priestly blessing. Numbers 6:25.
"Blood" refers to the blood of a goat or of a bullock. He entered often, again and again, every year.
The first word in Greek, translated "then," is "because in that case" or "for otherwise." It introduces the apodosis of a contrary to fact condition. The first part of verse 26 says implicitly that Christ does for Adam. The type, the Levitical Priesthood, goes back only to Sinai. But the antitype, Christ, goes back to the foundation of the world. The type covered a span of only 1500 years. But the antitype applies to all of history and will reach into eternity.
Now the second part of verse 26. Note carefully the order of the words. "End of the ages" does not denote the end of time. That comes at the end of verse 28. It denotes the final age of the world, the period of redemption, the time since Christ was crucified. It means "at the consummation of the ages."
Kretzmann: In the fulness of the times, in the period of the world when all the types and prophecies of the Old Testament find their interpretation and fulfillment, in the period preceding the end of the world. All is now complete except His second coming.
Christ abolished death, 2 Timothy 1:10. He destroyed the works of the devil, 1 John 3:8. He removed sin, Hebrews 9:26. We are reminded of John 1:29.
Westcott: Each element in this sentence (verse 26b) brings out some contrast between the work of Christ and that of the Levitical High priests: 1) Their sacrifices were repeated year by year during a long period of preparation: His sacrifice was offered once for all at the close of the succession of ages. 2) They by their action called sins to mind: He annulled sin. 3) They provided typical atonement through the blood of victims: He provided an absolute atonement by the sacrifice of Himself. 4) With them the most impressive fact was the entrance into the darkness in which the Divine Presence was shrouded: With Him the manifestation on earth, still realized as an abiding reality, brought the Divine Presence near to men. Generally it is made plain that Christ accomplished all that the Levitical Service pointed to.
Look at 1 John 3:5.
"Is destined," an impersonal verb denotes that which, in the counsel of God, is a fixed principle. Note that it is present tense. The subject of this verb is "to die" and note its tense, aorist, just once. It is emphasized by the adverb "once," used frequently in Hebrews (6:4; 9:7,26,27,28; 10:2; 12:26,27).
The text goes on to say: "And thereafter (after death) judgment." This verse is an axiom. No one in his right mind would deny the truth of this statement. Our Catechism rightly uses this verse as a proof text that man's judgment comes immediately after death.
The "Just as" at the beginning of verse 27 draws a conclusion. The precise point of comparison between verses 27 and 28 is the finality of Christ's work.
Here the point of comparison is applied. He is called "Christ," not "Jesus." Just once He was offered. "To take away" is "to do away with." Here "many" is used as at Isaiah 53:11-12 and Romans 5:16 and 19, where "many" is contrasted with "one." The universal atonement is not denied but emphasized.
He will appear a second time "not for the purpose of atoning for sin." On the second coming look at Romans 8:19,23,25; 1 Corinthians 1:7; Galatians 5:5; Philippians 3:20. His second coming is for "the purpose of deliverance." It does not denote salvation, but final deliverance for God's children, similar to the use of the term in Luke 21:28.
Verses 24-28a denote universal redemption. But 28b denotes the particular deliverance of the believers in Christ. When He appears it will be the second coming, not for the purpose of suffering, and for the final deliverance of God's children. We think of John 19:20 and Galatians 1:1-5.
What single event still needs to be fulfilled? Only the second coming. In the Nicene Creed only the last sentence has the words "look for." All else is already fulfilled.