5:9

after he had been made perfect: God’s Son was created as a perfect spirit being; later as a human, he “committed no sin” throughout his earthly life. (1Pe 2:22) However, in order to fulfill a special assignment, he had to be “made perfect” in another sense. He needed to become perfectly suited to serve as High Priest in behalf of mankind. What Paul here teaches harmonizes with the meaning of the Greek words rendered “make perfect,” “perfect,” and “perfection.” Among other things, they can convey the ideas of being complete, reaching a goal, and accomplishing a purpose. (Compare study note on 1Co 13:10.) As a human, Jesus became perfectly qualified to serve as a sympathetic high priest by keeping integrity in the face of every trial, even death.​—Heb 2:17; 4:15; 5:10; see study note on Heb 2:10.

he became responsible for everlasting salvation: Jehovah God is the ultimate Source of “everlasting salvation.” (Isa 45:17) However, Jesus is the means that his Father uses to make it possible for humans to be saved from sin and death, which they inherit from Adam. (Compare Lu 1:68, 69 and study note; 2:30.) In his capacity as High Priest, Jesus “became responsible” for assisting obedient humans to gain that salvation. Jesus is also called “the Chief Agent [or, “the Pioneer”] of . . . salvation.”​—Heb 2:10 and study note; see also study notes on Ac 3:15; 1Ti 1:1.