Hebrews 7:23-25 – The former priests were many in number, because they were prevented by death from continuing in office,  but he holds his priesthood permanently, because he continues forever.  Consequently, he is able to save to the uttermost those who draw near to God through him, since he always lives to make intercession for them.
Our great high priest lives forever. He lives to make intercession for us – forever. Jesus is able to save us completely because He has triumphed over death and as the One who lives forever is constantly before the throne of God interceding for the saints.
If you are a believer, you can start worrying if the work of Jesus is sufficient for you, when Jesus dies. And when will that be? Never. Your salvation and cleansing by God is guaranteed for as long as Jesus is alive. Since He lives forever that is how long He will stand before the throne of God and plead your case for you.
Our confidence before God is not a matter of our performance. It is bound up in the life, work, and acceptability of Jesus Christ. Obedience to Christ is not the ground of our salvation. It is the inevitable result of our salvation. The ground is Christ, His death and resurrection and His eternal intercession at the right hand of the Father as our great high priest. This is liberating stuff. We do not save ourselves. We trust Christ to save us. He does all the work. We hide in Him and trust the power of His work on our behalf.
What the writer to the Hebrews is telling us here is that Christ has done all that could be done and now presents His death for us as a sufficient atonement for our sins. And it is sufficient. And it will always be sufficient. And we are saved as long as Jesus is alive. What a great salvation.