19 Then, the same day at evening, being the first day of the week, when the doors were shut where the disciples were assembled, for fear of the Jews, Jesus came and stood in the midst, 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 So Jesus said to them again, "Peace to 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, they are forgiven them; if you retain the sins of any, they are retained."
doors were shut (v. 19) = in Greek, barred
fear of the Jews (v. 19) — A report was circulating that the disciples had taken the body (Matthew 28:13).
Peace be with you (v. 19) — the standard greeting for Jews
peace (v. 19) — The disciples' failures, abandonment of Jesus and denials had all been forgiven
His hands and His side (v. 20) — This was no ghost or illusion. The disciples were finally convinced the resurrection was true (John 16:16, 20).
The commentaries are all over the place regarding verse 22. I think this is where the disciples were indwelled. In Acts 2, they were filled and given special powers. We, today, can be indwelled (and are at salvation) but not filled.
The doors needed not to be unbolted to let Him in. The text makes it clear that the doors remained closed, especially when He appeared again, "the doors being shut, He stood in the midst." The risen body of our Lord was not bound or controlled by the laws which bind and control the natural body of man. He could enter in, without an angel coming and opening the doors for Him. The risen body is a miracle in itself. That body is supernatural. While it was a real human body, a material body, a body which could be touched and handled, which had bones and flesh, yet it was a spiritual body, endowed with powers which are above our understanding. In that body He appeared and disappeared, was visible and invisible, entered through a close door and departed through a closed door, and it could finally be lifted up, no law of gravitation putting a check upon it, and carried in a moment, in the twinkling of an eye, through the heavens into heaven itself. The resurrection body is a great mystery and will remain a mystery till we look no longer into a glass darkly. When that blessed day comes, we shall have the redemption of our body and that future body, in which we shall spend eternity, will be link unto His glorious body (Philippians 3:21). Then we shall know. Then we shall live as He lives, in a resurrection body of glory. — The Gospel of John, by Arno Clemens Gaebelein, page 392
But what did our Lord mean when He spoke these words [verse 23]?
He conferred upon them undoubtedly the power of declaring through the preaching of the Gospel, in the power of the Holy Spirit, whose sins are forgiven, and whose sins are not forgiven. Their preaching in the Book of Acts gives us examples of this declaration. Peter said in the house of Cornelius, "Whosoever believeth on Him shall receive remission of sins." When Paul preached the Gospel in Antioch of Pisidia, he said, "Through this man is preached unto you the forgiveness of sins," and later he said to the jailor in the Macedonian city, "Believe on the Lord Jesus Christ and thou shalt be saved." They declared that those who believe have their sins remitted, and, naturally, those who do not believe their sins are retained. — The Gospel of John, by Arno Clemens Gaebelein, page 396-397
The Greek word here used [for "breathed" in verse 22] is employed nowhere else in the New Testament, but is the very one used by the Septuagint translators of Genesis 2:7; "And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul." There, man's original creation was completed by this act of God; who, then, can fail to see that here in John 20, on the day of the Savior's resurrection, the new creation had begun, begun by the Head of the new creation, the last Adam acting as "a quickening spirit" (1 Corinthians 15:45)! The impartation of the Holy Spirit to the disciples was the "firstfruits" of the resurrection, as well as a proof that the Spirit proceeds from the Son as well as the Father — wonderful demonstration of the Savior's Godhead! — Exposition of the Gospel of John, by Arthur W. Pink, page 286
From this moment, the Spirit dwelt within them. We have been accustomed to look upon the change which is so apparent in the apostles as dating from the day of Pentecost, but the great change had occurred before then. Read the closing chapters of each Gospel and the first of Acts, and the proofs of this are conclusive. Their irresolution, their unbelief, their misapprehensions, were all gone. When the cloud finally received the Savior from their sight, instead of being dispersed in consternation "they worshiped Him" and "returned to Jerusalem with great joy" (Luke 24:52) — this was "joy in the Holy Spirit" (Romans 14:17): Moreover, they continued "with one accord in prayer and supplication" (Acts 1:14) — this was the "unity of the Spirit in the bond of peace" (Ephesians 4:3). Peter has a clear understanding of Old Testament prophecy (Acts 1:20) — this was the Spirit guiding into the truth (John 16:13). And these things were before Pentecost. What happened at Pentecost was the baptism of power, not the coming of the Spirit to indwell them! — Exposition of the Gospel of John, by Arthur. W. Pink, page 286-287