Question: "What does the Bible say about confession of sin to a priest?"

Answer: The concept of confession of sin to a priest is nowhere taught in Scripture. First, the New Testament does not teach that there are to be priests in the New Covenant. Instead, the New Testament teaches that all believers are priests. 1 Peter 2:5-9 describes believers as a “holy priesthood” and a “royal priesthood.” Revelation 1:6 and 5:10 both describe believers as “a kingdom and priests.” In the Old Covenant, the faithful had to approach God through the priests. The priests were mediators between the people and God. The priests offered sacrifices to God on behalf of the people. That is no longer necessary. Because of Jesus’ sacrifice, we can now approach God’s throne with boldness (Hebrews 4:16). The temple veil tearing in two at Jesus’ death was symbolic of the dividing wall between God and humanity being destroyed. We can approach God directly, ourselves, without the use of a human mediator. Why? Because Jesus Christ is our great High Priest (Hebrews 4:14-15; 10:21), and the only mediator between us and God (1 Timothy 2:5). The New Testament teaches that there are to be elders (1 Timothy 3), deacons (1 Timothy 3), bishops (Titus 1:6-9), and pastors (Ephesians 4:11) – but not priests.

When it comes to confession of sin, believers are told in 1 John 1:9 to confess their sins to God. God is faithful and just to forgive our sins as we confess them to Him. James 5:16 speaks of confessing our trespasses “to one another,” but this is not the same as confessing sins to a priest as the Roman Catholic Church teaches. Priests / church leaders are nowhere mentioned in the context of James 5:16. Further, James 5:16 does not link forgiveness of sins with the confession of sins “to one another.”

The Roman Catholic Church bases their practice of confession to a priest primarily on Catholic tradition. Catholic do point to John 20:23, “If you forgive anyone his sins, they are forgiven; if you do not forgive them, they are not forgiven." From this verse, Catholics claim that God gave the apostles the authority to forgive sins, and that authority was passed on to the successors of the apostles, e.g. the bishops and priests of the Roman Catholic Church. There are several problems with this interpretation. (1) John 20:23 nowhere mentions confession of sin. (2) John 20:23 nowhere promises, or even hints, that the authority to forgive sins would be passed on to the successors of the apostles. Jesus’ promise was specifically directed to the apostles. (3) The New Testament nowhere states that the apostles would even have successors to their apostolic authority. Similarly, Catholics point to Matthew 16:19 and 18:18 (binding and loosing) as evidence for the Catholic Church’s authority to forgive sins. The same three above points apply equally to these Scriptures.

Again, the concept of confession of sin to a priest is nowhere taught in Scripture. We are to confess our sins to God (1 John 1:9). As New Covenant believers, we do not need mediators between us and God. We can go to God directly because of Jesus’ sacrifice for us. 1 Timothy 2:5, “For there is one God and one mediator between God and men, the man Christ Jesus.”

Recommended Resource: The Gospel According to Rome: Comparing Catholic Tradition and The Word of God by James McCarthy.

http://www.gotquestions.org/confession-sin-priest.html

"...The Bible teaches us that "without shedding of blood is not remission" of sin (Heb 9:22), but also that "it is not possible that the blood of bulls and of goats should take away sins" (Heb 10:4). Forgiveness is based on repentance, recognizing that one has offended God and turning from that sin. The very fact that blood sacrifices continued on a daily basis and by the high priest for the sins of all the people once a year, proves that those sacrifices were imperfect and insufficient. Moreover, since repentance was seldom a part of Israel's sacrifice, and even though the sacrifices continued, God judged the nation's sins by sending the people into captivity.

Thankfully, Christ acted to fulfill the law and eliminate the sacrificial system with the final sacrifice. "We are sanctified through the offering of the body of Jesus Christ once for all" (Heb 10:10). "There is no more offering for sin" (v. 18). He has assumed the office of High Priest, administered the final sacrifice, and made priests of all His followers. Just as the Old Testament priest, we have "boldness to enter into the holiest by the blood of Jesus" (v. 19). We have no need for human intermediaries; we are believer-priests with a High Priest who has made it possible for us to come on His merits to the Father. Just as He gave certain authority to the Old Testament priests, He has given us this authority (Days of Praise, 14 Nov 2009)."
 

Rome's Priests are False Mediators

"Every Roman Catholic priest is said to have the task of not only "representing Christ, before the assembly of the faithful, but also of acting in the name of the whole Church when presenting to God the prayer of the Church, and above all when offering the Eucharistic sacrifice" (1552).  In this way, Catholics are totally dependent upon priests for their salvation.  It is the priest who is said to cause regeneration and justification in baptism (1992, 1213); absolve mortal sin in the confessional; dispense the body and blood of Jesus in the Eucharist; impart the Holy Spirit in the sacrament of Confirmation; and offer the sacrifice of the Mass for souls suffering in purgatory.  It is no wonder why Catholics trust their religion and the priests as mediators to usher them into heaven.  Yet, the truth must be told:  "There is one God, and one mediator also between God and men, the man Christ Jesus" (1 Tim. 2:5). By faith in the the blood of Jesus, the High Priest, believers can go boldly into God's presence without an earthly priest (Heb. 10:19-20).  Since the resurrection of the one mediator, there is no need for a mediating priesthood." Full text:   God's Word Exposes Ten Fatal Flaws of Catholicism