Q. 1. I heard that there are two kinds of priesthood. It was even said that we lay people are part of one of the two priesthoods. Can you please clarify that?
A. 1. Indeed, there are two kinds of priesthood. Most Christians are familiar with the first kind of priesthood that consists of the clergy. It is the order of men who are set apart for sacred offices. Their calling is often referred to as a "calling to the priesthood." They are known for administering the Sacraments in the Catholic Church.
In 1 Peter 2:5, we find a reference to another kind of priesthood that is referred to as "the common priesthood." "(4) Come to him, a living stone, though rejected by mortals yet chosen and precious in God's sight, and (5) like living stones, let yourselves be build into a spiritual house, to be a holy priesthood, to offer spiritual sacrifices acceptable to God through Jesus Christ."
The 1968 edition of "The Jerome Biblical Commentary" views this priesthood in the following manner:
Catholics are exhorted to live in holiness as befits the Chosen Race and the Royal Priesthood. They are "living stones," not just as persons contrasted with the inanimate blocks used in pagan temples but as persons vivified by the life of Christ Himself in baptism. So united to Christ, the Cornerstone, they form a new unit, which the author proceeds to describe in several mixed images. They form first a spiritual house, a new temple in which the bonding material is not race, but the Spirit. By baptism Christians are called and destined to the service of the priesthood. As a kingdom of priest (royal priesthood), Catholics are called to a priestly destination. By their baptism, they are deputed to the cultic service of God in Christ. It is at once a royal and a priestly destination. They are to offer themsevles as a "living sacrifice" that would be holy and acceptable to God; this is to be their spiritual worship. The baptized Christian is therefore empowered and expected to live his whole life as if he were a cultic act, continuing in a sense the sacrifice of Christ, but also manifesting to the world that he is marked for the service of Christ.
All Catholics, male and female, automatically belong to the second kind of priesthood by their baptism.