Therefore he is the mediator of a new covenant, so that those who are called may receive the promised eternal inheritance, since a death has occurred that redeems them from the transgressions committed under the first covenant. Hebrews 9:15 ESV

... but he holds his priesthood permanently since he lives forever. 

So he is able to save completely those who come to God through him, 

because he always lives to intercede for them. Hebrews 7:24-25 NET