Non-Catholics rejected the sacrament of confession saying that only God can forgive sins. The Jews said exactly the same thing to Christ and were rebuked for it, “Why does this man speak thus? It is blasphemy! Who can forgive sins but God alone?” (Mark 2:7, Luke 5:21, Matthew 9:3). Jesus could have easily told them that He was God and that was why He was able to forgive sins, but He didn’t do that because He had something else to show them. Jesus replied to them, “Why do you question thus in your hearts? Which is easier, to say to the paralytic, ‘Your sins are forgiven’, or to say, ‘Rise take up your pallet and walk’? But so that you may know that the Son of man has the authority to forgive sins on earth’ —He said to the paralytic—’I say to you, rise, take up your pallet and go home’ (Mark 2:9-11, Matthew 9:4-6, Luke 5:22-24). And he rose and went home. When the crowds saw it, they were afraid, and they glorified God, who had given such authority to men” (Matthew 9:7-8). The authority was given to men (plural), the Father gave it to Jesus and the Lord gave it to His Church.
In John 20:21-22, Jesus said to His apostles, “’Peace be with you. As the Father has sent me, even so I send you.’ And when He said this He breathed on them, and said to them, ‘Receive the Holy Spirit. If you forgive the sins of any they are forgiven; if you retain the sins of any, they are retained’”. In Matthew 28:19, Jesus said, “All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations”. The Lord knew that it would be necessary to continue the divine mission even after the death of the Apostles. That is why Jesus promised: “lo, I am with you always, to the close of the age” (Matthew 28:20). Thus, Christ’s authority continues in the Church until the end of times, not just until the death of the apostles. This authority was passed on from the apostles to their successors in the Church.
St. Paul stated how he was given the power to forgive sins from Jesus, “for if I forgave anything, to whom I forgave it, for your sakes forgave I it in the person of Christ (2 Corinthians 2:10) and all this is from God, who through Jesus Christ reconciled us to Himself and gave us this ministry of reconciliation (2 Corinthians 5:18). The apostles’ power to forgive sins didn’t come from themselves, it came from God. And the blessed apostle continued, “So we are ambassadors for Christ (2 Corinthians 5:20). Thus, Christ gave to His Church the power to forgive and retain sins. Going to a priest to have sins forgiven is indeed going to Christ because the priest, like St. Paul, is acting “in the person of Christ.”
When St. Paul came to Ephesus, believers confessed their sins: Many of those who were now believers came, confessing and divulging their practices (Acts 19:18). Why would these believers (they were already Christians) confess their sins in the presence of the Apostles if it were enough just to pray to God?
In his letter, James said, “Is any man sick among you? Let him bring in the priests (Greek, presbuteros) of the church, and let them pray over him, anointing him with oil in the name of the Lord. And the prayer of faith shall save the sick man; and the Lord shall raise him up; and if he be in sins they shall be forgiven him. Confess therefore your sins one to another; and pray one for another, that you may be saved (James 5: 14-16). The word presbuteros, often translated “elders,” is origin for the English word “priest” through the German word “priester”. Notice in the verse that the confession of sins was to occur only after the priests were called.
When a person becomes a Christian through baptism, he becomes part of a family or household (cf. 1 Timothy 3:15), which is the Church. Each Christian is part of a body, “for by one Spirit we are all baptized into one body” (1 Corinthians 12:13). Thus, if one commits a sin, he does not only offend God, but also hurts the entire body: “If one member suffers, all suffer together with it (1 Corinthians 12:26). No one can say that he doesn’t need the Church, but just Christ. Remember, “the eye cannot say to the hand, ‘I have no need of you’, nor again the head to the feet, ‘I have no need of you'” (1 Corinthians 12:21). Why? Because the Church has the authority to reconcile the fallen members to the Body and then finally to God Who is the Head of that Body. Jesus told His apostles, “but if the offender refuses to listen even to the church, let such a one become to you as a Gentile and a tax collector” (Matthew 18:17). Notice those big words: EVEN TO THE CHURCH.
The Holy Scripture declares that “If we confess our sins, he is faithful and just, to forgive us our sins, and to cleanse us from all iniquity” (1 John 1:20). This verse makes no sense if all of the sins (past and future) are forgiven when one becomes a Christian. When a person becomes Christian through baptism, he is cleansed of all “past sins” (cf. 2 Peter 1:9). But how about the sins to be committed in the future?
When a Christian first realizes that he has sinned and he is sorry for that sin, he should then pray to God for forgiveness. If the sin is a serious one, the person should also go to a priest as soon as possible. Jesus never told anyone to go and just pray to God until they feel forgiven. When the woman was caught in adultery by the scribes, the Lord said: “Neither will I condemn thee. Go, and now sin no more” (John 8:11). She needed to hear it and not just to feel being sorry by herself, i.e. not judging her own heart. St. Paul wrote to the Corinthians: “neither do I judge my own self. For I am not conscious to myself of any thing, yet am I not hereby justified; but he that judgeth me, is the Lord. Therefore judge not before the time; until the Lord come, who both will bring to light the hidden things of darkness, and will make manifest the counsels of the hearts; and then shall every man have praise (1 Corinthians 4:3-5).
There is sin in the world today just as in the first centuries of Christianity, so the divine remedy for sin is still necessary. Since the priest has the authority to forgive or retain sins, it must be necessary to tell the sins to the priest so he can decide which sins to forgive and which sins to retain. Jesus knew that since men still sin after baptism, the sacrament of confession is therefore absolutely necessary.