The former priests were many in number, because they were prevented by death from continuing in office; but he [Jesus] holds his priesthood permanently, because he continues for ever. Consequently he is able for all time to save those who draw near to God through him, since he always lives to make intercession for them. Heb. 7:23-25, RSV.
"He is able"! Possibly the most profound words in human history.
Jesus is able to "save them to the uttermost that come unto God by him" (Heb. 7:25, KJV), because He not only offered a better sacrifice, but also has a better priesthood, one that will continue until sin is no more and atonement is complete.
"He is able." Those who trust in Jesus need not fear. His hand is not shortened that it cannot save (Isa. 50:2). Unlike the Levitical priests who died, the resurrected Jesus is always there for His people.
At this point we need to ask what it means to be saved "to the uttermost" or "completely" (Heb. 7:25, NIV). We see one aspect reflected in the Revised Standard Version's translation: "He is able for all time to save those who draw near to God through him." That meaning is certainly in the context, but extent in time doesn't capture the full contextual implications. Hebrews 7:27 goes on to speak of human sin and the ineffectiveness of the Levitical sacrifices as opposed to the efficacious once-for-all sacrifice of Jesus that solved the sin problem once and for all. Thus Christ's saving "to the uttermost" implies that Jesus rescues us from all that we need redemption from--that His salvation is complete deliverance from the sin problem.
W. H. Griffith Thomas, combining that thought with the temporal one, writes that "looking back over the past, we have been saved from the condemnation and guilt of sin; looking round upon the present, we are being saved from the power, love, and defilement of sin; looking forward to the future, we shall be saved from the very presence of sin in the glorified state above."
In short, Jesus is able to "save to the uttermost" not only because He lives, but also because He interceded for those who come to Him. He returned to heaven as a victorious conqueror who died and rose again and sits on God's throne as an equal.
For all of those reasons and more, "He is able"!