Updated: May 27, 2021
By Luke Lancaster
Many of our non-Catholic friends can poke at the Catholic doctrine of the Priesthood. Most churches in the United States simply have a pastor or elder that leads the church, but Catholics have something different. We use the unique word "priest" for our leadership. Why, though? First, let's get a definition of the word.
Merriam-Webster defines "priest" as "one authorized to perform the sacred rites of a religion especially as a mediatory agent between humans and God." The priest is a mediator between God and man. According to Scripture, Jesus is that mediator, for He is the "one mediator between God and men" (1 Timothy 2:5). Jesus also performed the "sacred rites" of Judaism by making a sacrifice, but a sacrifice like no other. He acted as a priest offering the sacrifice of Himself on Calvary.
However, Jesus never wants to act alone. He always wants us to participate in His works. This is why the Church is called His Body on earth (1 Corinthians 12:27). All baptized Christians were put "into" Christ (Galatians 3:28). If this is the case, and Christ is a priest, then Christians were placed into Christ's priesthood as well. They would be acting as mediators between God and man (1 Peter 2:9). So, all Christians are lower-case "priests." Nevertheless, certain men in particular are called to participate more deeply in Christ's priesthood.
Consider St. Paul, who refers to his ministry with a certain "priestly" flavor. He says in Romans 15:16 that he is a "minister of Christ Jesus to the Gentiles in the priestly service of the gospel of God." St. Paul's actions on earth are "priestly." He stands in-between God and the Gentiles of the world. Our Catholic priests local to us do the same type of ministry as Paul did, leading us Gentiles to the Lord. St. Paul also uses the word "minister" to describe his works to the Christian churches which he served. Who else is a minister? Jesus. He is the priestly "minister" for us in Heaven (Heb. 8:1-2). So, Paul definitely saw himself as being "in Christ" the priest.
St. Paul performed the "sacred rites" of Christianity was well. For since Paul was "in Christ" as a participator in Christ's priesthood, he could stand in the place of Jesus and offer up the sacrifice of Christ's "Body" and "Blood" on Calvary (1 Cor. 11:23-26). So also, our Catholic Priests follow in the footsteps of Christ and Paul. They also offer the Body and Blood of the Lord, which was accomplished on Calvary to God on behalf of men. They stand in Christ's role as mediator.
This is why Catholic (upper-case) Priests are called "priests." There are many other proofs for this, so check out the other articles on this website that point out the biblical basis for the Catholic priesthood. If you are wondering why Paul does not use the word "priest" in Eph. 4:11, see this article.