Four prerequisites are laid out for the priesthood in Hebrews 5:1-4.
- For every high priest taken from among men is appointed on behalf of men in things pertaining to God, in order to offer both gifts and sacrifices for sins; he can deal gently with the ignorant and misguided, since he himself also is beset with weakness; and because of it he is obligated to offer sacrifices for sins, as for the people, so also for himself. And no one takes the honor to himself, but receives it when he is called by God, even as Aaron was. - Hebrews 5:1-4
First, a high priest must be human — every high priest taken from among men. As previously stated, the priest represents man to God — appointed on behalf of men. In order to do that, he must be human. The term every (pás) indicates that this principle applies to all priesthoods.
Second, a high priest must make offerings and sacrifices — gifts and sacrifices for sins. The high priest was responsible for offering sacrifices for the people and for himself.
Third, a high priest must be sympathetic — deal gently. Deal gently (metriopathéō) means to show graciousness. A priest must show graciousness towards the ignorant (agnoéō) - those lacking in knowledge of sin and the misguided (planáō) - those who are deceived by sin. The reason for showing graciousness is because a human priest is subject to the same weaknesses (asthéneia) or faults as those to whom he ministers.
Fourth, a high priest must be appointed by God — he is called by God. God specifically called Aaron (and his descendants) to serve as high priest.