Actually, the answer is not that far off from what it is today. The priest’s main duty was to act as an intermediary between God and man. During the time of the Old Testament, their main focus was upon the offering of sacrifices which, were intended to restore the personal relationship between God and the individual; re-establishing the threatened covenant between God and His people. Priests received gifts, made offerings, manipulated blood, and led the people in their required ritual. As St. Paul writes in the Book of Hebrews, they were “mediators” (9:15).
The role of the priesthood also included teaching. Priests ensured that the correct ritual was being observed and interpreted for the people what God was saying to them through Scripture, sacramental worship, and with the celebration of feasts. They taught that sacrifices were viewed as acts of repentance, showing a new commitment to obedience.
As well as being teachers the priests were expected to live an exemplary life within the community, scrupulously observing the law they were ordained to uphold. They were to maintain a separation and holiness which reflected God Himself, into Whose near presence they so often came.
In offering the sacrifices the priests were regarded as both representing Israel, standing before God on behalf of His people, and making the offering while the rest of the congregation acknowledged what was being done in their name. In their representative capacity before God, the priests’ duty was to make intercession for those whose
sacrifices they offered.
Interestingly enough, when priests failed in their above-listed capacity to teach and live righteously, God’s failsafe was to call forth prophets to chastise and bring the people back to God.