The priesthood in ancient Israel, as established in the Old Testament, was a divinely ordained institution with the descendants of Aaron, the brother of Moses, serving as the primary priests. This lineage is central to the religious and ceremonial life of Israel, as outlined in the Pentateuch, particularly in the books of Exodus, Leviticus, and Numbers.

Divine Appointment and Duties

The appointment of Aaron and his sons as priests is recorded in Exodus 28:1, where God commands Moses, "Bring near to you your brother Aaron and his sons with him, from among the Israelites, to serve Me as priests—Aaron, Aaron’s sons Nadab and Abihu, Eleazar and Ithamar." This divine selection underscores the sacred nature of the priesthood, which was not a position to be assumed by personal ambition but by divine calling.

The primary duties of the Aaronic priests included offering sacrifices, maintaining the sanctuary, and teaching the Israelites God's laws. Leviticus 10:11 states, "You must teach the Israelites all the statutes that the LORD has given them through Moses." The priests acted as mediators between God and the people, performing rituals that symbolized atonement and reconciliation.

Ceremonial Garments and Consecration

The priests were distinguished by their ceremonial garments, which were designed for "glory and beauty" (Exodus 28:2). These garments included the ephod, breastplate, robe, tunic, turban, and sash, each with specific symbolic significance. The consecration of Aaron and his sons is detailed in Leviticus 8, where they were anointed with oil and sanctified for their sacred duties.

The High Priest

Among the descendants of Aaron, the High Priest held a unique and elevated role. The High Priest was the only one permitted to enter the Holy of Holies in the Tabernacle, and later the Temple, once a year on the Day of Atonement (Yom Kippur) to make atonement for the sins of the people (Leviticus 16). This role was first held by Aaron and passed down through his lineage.

The Priesthood and Holiness

The priesthood was characterized by a high standard of holiness and purity. Leviticus 21 outlines specific regulations for the priests, emphasizing their need to remain ceremonially clean and morally upright. They were to avoid defilement from contact with the dead, maintain marital purity, and adhere to dietary laws.

Challenges and Failures

Despite their sacred calling, the Aaronic priesthood faced challenges and failures. The sons of Aaron, Nadab and Abihu, offered unauthorized fire before the Lord and were consumed by divine fire as a result (Leviticus 10:1-2). This incident serves as a sobering reminder of the seriousness of their duties and the holiness required of those who serve God.

The Priesthood in Transition

The Aaronic priesthood continued through the history of Israel, adapting to changes such as the establishment of the Temple in Jerusalem. However, the priesthood faced corruption and decline, as seen in the accounts of Eli's sons (1 Samuel 2) and the later critiques by the prophets.

In the New Testament, the role of the priesthood is transformed through the person and work of Jesus Christ, who is described as a High Priest in the order of Melchizedek (Hebrews 5:10). This transition marks a shift from the Aaronic priesthood to a new covenant, where all believers are considered a "royal priesthood" (1 Peter 2:9), yet the historical and theological significance of the Aaronic priests remains foundational to understanding the biblical narrative.