John 20:21–23 (NKJV) 

21So Jesus said to them again, “Peace to you! As the Father has sent Me, I also send you.” 22And when He had said this, He breathed on them, and said to them, “Receive the Holy Spirit. 23If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained.” 

One of the great controversies that surrounded Jesus’ ministry was the forgiveness of sins. Recall that when a paralytic was brought to Jesus and let down through the roof into the house where Jesus was teaching, Jesus looked at the man and declared, “My son, your sins are forgiven you.” Immediately, the Pharisees began questioning among themselves, “Who does this man think he is? Who can forgive sins but God alone?” (Mk 2:7)

The Pharisees’ question was entirely reasonable. While I can forgive you for intentionally breaking my nose, I cannot forgive you for breaking my neighbor’s – I wasn’t the one wronged, so how can I forgive you? The same principle applies for sins against God: only God can forgive those who sin against Him. So how can we know whether God has forgiven us? Who speaks for God on earth?

In the old covenant, the Aaronic priests spoke for God. God used the sacrificial system and the priests to assure people of forgiveness. 

5‘And it shall be, when [someone] is guilty in any of these matters, that he shall confess that he has sinned in that thing; 6and he shall bring his trespass offering to the Lord for his sin which he has committed, a female from the flock, a lamb or a kid of the goats as a sin offering. So the priest shall make atonement for him concerning his sin. (Leviticus 5:5–6) 

The priest shall make atonement for him; over the sacrifice, the priest would announce, “Believe God’s promise! He has provided a substitute to bear the guilt of your sin. You are forgiven!” This feature of the old covenant helps us understand why the Pharisees were disturbed by Jesus’ forgiveness of the paralytic: Jesus was not an Aaronic priest, nor was He at the temple where a sacrifice was being offered. So how dare He presume to speak for God? “Who does this man think he is? Who can forgive sins but God alone?”

Jesus knew the Pharisees’ doubts; He knew their questions. So He asked, “Which is easier to say to this man, ‘Your sins are forgiven,’ or, ‘Arise, take up your mat and walk’? But that you may know that the Son of Man has authority on earth to forgive sins,” (he said to the paralytic), “’Arise, take up your mat and walk.’ And immediately the man arose, took up his mat, and walked” (Mk 2:9-12). According to Jesus, the healing of the paralytic proved that the Son of Man has authority on earth to forgive sins. Jesus now speaks for God. With these words and actions, Jesus was announcing the end of the old covenant, the sacrificial system, and the Aaronic priesthood. Now, in the Messianic Age, the forgiveness of sins is declared in Jesus’ Name, based on His once-for-all sacrifice. Jesus speaks for God.

So that brings us to our text in John 20. After Jesus had been crucified and then risen from the dead, He spoke to the Twelve. “As the Father has sent Me, so I send you…”  Jesus commissioned the Twelve as His representatives; they were to speak for God in the world and to declare the forgiveness of sins in His Name. “Receive the Holy Spirit,” Jesus said. “If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained.” In other words, the sacrificial system has forever come to an end and the forgiveness of sins is now preached to all nations based on the sacrifice of Christ alone.

So every Lord’s Day, following our confession, I have the privilege of reminding you, assuring you, that through the sacrifice of Jesus Christ, there really is forgiveness with God. If you acknowledge your sin and turn from it, seeking God’s forgiveness through Jesus Christ, then you are forgiven. My word does not grant forgiveness; only the sacrifice of Jesus can do that. My word simply reminds you of God’s promise and summons you to believe His word: all those who trust in the once-for all sacrifice of Jesus shall be forgiven and cleansed. Your calling is to hear that promise, even as the paralytic heard the words of our Lord, and to believe Him. “My son, your sins are forgiven.”

So reminded that God offers forgiveness only through the sacrifice of His Son Jesus, let us continue to confess our sins in His Name, not denying or hiding or minimizing or medicating them but trusting that God will indeed forgive all those who confess their sins in Jesus’ Name. And as you are able, let us kneel as we confess our sins.