Every high priest is taken from among men and made their representative before God, to offer gifts and sacrifices for sins.  He is able to deal patiently with the ignorant and erring, for he himself is beset by weakness and so, for this reason, must make sin offerings for himself as well as for the people.  No one takes this honor upon himself but only when called by God, just as Aaron was.

In the same way, it was not Christ who glorified himself in becoming high priest, but rather the one who said to him: “You are my Son; this day I have begotten you;” just as he says in another place: “You are a priest forever according to the order of Melchizedek.”