"19 On the evening of that day, the first day of the week, the doors being locked where the disciples were for fear of the Jews, Jesus came and stood among them and said to them, “Peace be with you.” 20 When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord. 21 Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending 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, they are forgiven them; if you withhold forgiveness from any, it is withheld.”
24 Now Thomas, one of the Twelve, called the Twin, was not with them when Jesus came. 25 So the other disciples told him, “We have seen the Lord.” But he said to them, “Unless I see in his hands the mark of the nails, and place my finger into the mark of the nails, and place my hand into his side, I will never believe.”
26 Eight days later, his disciples were inside again, and Thomas was with them. Although the doors were locked, Jesus came and stood among them and said, “Peace be with you.” 27 Then he said to Thomas, “Put your finger here, and see my hands; and put out your hand, and place it in my side. Do not disbelieve, but believe.” 28 Thomas answered him, “My Lord and my God!” 29 Jesus said to him, “Have you believed because you have seen me? Blessed are those who have not seen and yet have believed.”
30 Now Jesus did many other signs in the presence of the disciples, which are not written in this book; 31 but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name."
John 20:19-31
What are we to say about 23? It is very salutary to read Calvin's commentary on this verse. He points out that there is no foundation whatever for supposing that Christ imparts the power to forgive sins to any man. Who can forgive sins but God alone? What is referred to therefore is the proclamation of the forgiveness of sins. Interestingly enough, this is what Luke seems to indicate also (24:46, 47). If it be thought that this is less than convincing as an interpretation, it may be asked: If the words mean that the power to forgive sins was in fact bestowed by the disciples here, how is it that it is nowhere recorded in the Acts of the Apostles as having been exercised in the early Church? What we do find, however, in Acts, is Peter and the other apostles using the keys of the kingdom, opening the kingdom of heaven to men by the proclamation of the word of forgiveness in the gospel. For the parallel emphasis of the retention of sins, see Acts 13:46, 47, 51 and 2 Corinthians 2:15, 16. We should note finally, in this section of the passage (21), that Jesus said to the disciples, 'As My Father hath sent Me, even so send I you'. How did the Father send Him? He sent Him to walk the way of the cross. Jesus sends us that way too, and it is as we are prepared to walk that way that the reception of the Holy Spirit becomes relevant. It is one of the most important lessons to learn, that we cannot without danger and loss separate the doctrine of the Holy Spirit from the death and resurrection of Christ. They belong together, and what God hath joined together, let not man put asunder.