Does John 20:23 mean that Catholic priests can forgive sins?  No, it does not.

“If you forgive the sins of any, their sins have been forgiven them; if you retain the sins of any, they have been retained,” (John 20:23).

Context is king when interpreting scripture, and this is no exception.  Let’s take a look.

“When therefore it was evening, on that day, the first day of the week, and when the doors were shut where the disciples were, for fear of the Jews, Jesus came and stood in their midst, and said to them, “Peace be with you.” 20 And when He had said this, He showed them both His hands and His side. The disciples therefore rejoiced when they saw the Lord. 21 Jesus therefore said to them again, “Peace be with you; as the Father has sent Me, I also send you.” 22 And when He had said this, He breathed on them, and said to them, “Receive the Holy Spirit. 23 “If you forgive the sins of any, their sins have been forgiven them; if you retain the sins of any, they have been retained,” (John 20:19-23).

The context of John 20:23 is that Jesus was speaking to the disciples (v. 19).  He breathed on them to receive the Holy Spirit (v. 22).  There is nothing in here about priests having the authority to forgive sins.  There is nothing here (or anywhere else in the New Testament) about apostolic succession that says priests have the authority to forgive sins and that it is passed down.  The Bible does mention appointing elders (Acts 14:23; Titus 1:5), and that the disciples of Jesus had special authority (Matt. 16:18).  It speaks of the laying on of hands to receive the Holy Spirit (Acts 8:19) as well as ordaining men to the ministry (1 Tim. 4:14; 2 Tim. 1:6; Titus 1:5).  At best, the laying on of hands deals with ordination–not apostolic authority being passed down.  After all, they were ordaining elders and not apostles; and it was the apostles who were given the authority by Christ to do miracles and write scripture.  Nothing is said here about apostolic authority being passed down.

Have been forgiven

In John 20:23 the words “have been forgiven” is the single Greek word aphiami.  It is the perfect passive.  The perfect tense is “I have been.”  The pluperfect is “I had been.”  The perfect tense designates an action that occurs in the past and continues into the present, i.e., “I have been eating.”  The disciples were not doing the forgiving but pronouncing the sins that “have been” forgiven by God.  We find that the Psalmist says, “Help us, O God of our salvation, for the glory of Your name; and deliver us, and forgive our sins, for Your name’s sake,” (Psalm 79:9).  Also, consider the following:

“Jesus seeing their faith said to the paralytic, “My son, your sins are forgiven.” 6 But there were some of the scribes sitting there and reasoning in their hearts, 7Why does this man speak that way? He is blaspheming; who can forgive sins but God alone?” 8 And immediately Jesus, aware in His spirit that they were reasoning that way within themselves, *said to them, “Why are you reasoning about these things in your hearts? 9 “Which is easier, to say to the paralytic, ‘Your sins are forgiven’; or to say, ‘Arise, and take up your pallet and walk’? 10 “But in order that you may know that the Son of Man has authority on earth to forgive sins”—He said to the paralytic— 11 “I say to you, rise, take up your pallet and go home.” 12 And he rose and immediately took up the pallet and went out in the sight of all; so that they were all amazed and were glorifying God, saying, “We have never seen anything like this,” (Mark 2:5-12).

Jesus forgave sins; and the Scribes, students of the Law, rightly stated that only God forgives sins.  If they were wrong about that, then why didn’t Jesus correct them?  Instead, he affirms their claim, states he has the authority to forgive sins, and then heals the paralytic.  It should be clear that only God forgives sins; and Christians, as representatives of Christ, pronounce to people what has already been forgiven them by God.

So, John 20:23 is not saying that Catholic priests have the authority to forgive sins.  It is saying that Christian disciples have the authority to pronounce what sins “have been forgiven.”