I’m not sure why the Christian church has gotten into the sin-punishment business, because that was never what Jesus did. Penance isn’t the plan. He never judged anyone, so neither should Christians.
Jesus comes to save the lost – not berate them or make them feel bad.
11 For the Son of Man came to save that which was lost”
His disciples get angry when a Samaritan town rejects Jesus, and they want to call down the wrath of God to destroy the town. Jesus rebukes them because he is about saving lives, not destroying them.
51 It came to pass, when the days were near that he should be taken up, he intently set his face to go to Jerusalem 52 and sent messengers before his face. They went and entered into a village of the Samaritans, so as to prepare for him. 53 They didn’t receive him, because he was traveling with his face set toward Jerusalem. 54 When his disciples, James and John, saw this, they said, “Lord, do you want us to command fire to come down from the sky and destroy them, just as Elijah did?” 55 But he turned and rebuked them, “You don’t know of what kind of spirit you are. 56 For the Son of Man didn’t come to destroy men’s lives, but to save them.” They went to another village.
Jesus was not sent to judge us at all.
17 For God didn’t send his Son into the world to judge the world, but that the world should be saved through him.
Jesus teaches us what to do if a fellow-believer (what the term “brother” means) has done something harmful to you.
15 “If your brother sins against you, go, show him his fault between you and him alone. If he listens to you, you have gained back your brother. 16 But if he doesn’t listen, take one or two more with you, that at the mouth of two or three witnesses every word may be established. 17 If he refuses to listen to them, tell it to the assembly. If he refuses to hear the assembly also, let him be to you as a Gentile or a tax collector.
You are to stop associating with him. There is nothing in there about punishment or penance. The brother has proven through his actions that he isn’t interested in following the same rules as the group. He has chosen through his actions not to belong. You don’t need to do anything.
Jesus came to be a servant, not to be served. He has no desire to rule over anyone. This was illustrated in the story of the mother of the sons of Zebedee (James and John, two of his disciples) who wanted them to be specially honored –
27 Whoever desires to be first among you shall be your bondservant, 28 even as the Son of Man came not to be served, but to serve, and to give his life as a ransom for many.”
Jesus repeats his mission in the story of Zaccheus –
10 For the Son of Man came to seek and to save that which was lost.”
Jesus doesn’t judge anyone – even if they don’t believe in what he says.
47 If anyone listens to my sayings, and doesn’t believe, I don’t judge him. For I came not to judge the world, but to save the world.
Jesus again refuses to judge.
13 One of the multitude said to him, “Teacher, tell my brother to divide the inheritance with me.” 14 But he said to him, “Man, who made me a judge or an arbitrator over you?”
Since Jesus doesn’t judge, neither should Christians.
(All Bible translations are from the World English Bible – public domain)