Jesus said to his disciples:
"If your brother sins against you,
go and tell him his fault between you and him alone.
If he listens to you, you have won over your brother.
If he does not listen,
take one or two others along with you,
so that 'every fact may be established
on the testimony of two or three witnesses.'
If he refuses to listen to them, tell the church.
If he refuses to listen even to the church,
then treat him as you would a Gentile or a tax collector.
Amen, I say to you,
whatever you bind on earth shall be bound in heaven,
and whatever you loose on earth shall be loosed in heaven.
Again, amen, I say to you,
if two of you agree on earth
about anything for which they are to pray,
it shall be granted to them by my heavenly Father.
For where two or three are gathered together in my name,
there am I in the midst of them."
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We are all aware of the reality of sin. We have our own first hand experience of sinfulness. It is triggered by our human weakness, takes advantage of our passions, and betrays our logic. Yet the pain of sin is not only personal, it is always social. People are affected by our choices and the ones who feel the pain most are those closest to us. This experience of pain, suffering, and death was never the plan of God for us. St. Paul would say in Romans 6:23, "the wages of sin is death".
Jesus too is aware of human frailty. While we are easy to despair at our brokenness, Jesus provides the mechanism to heal wounds of division. It is an act of charity to correct one's brother or sister. It is an act of charity to lead them back to good and right. It might be difficult but it is the best course of action. It is the most just thing in the world because we are not anymore focusing on the consequence of sin. After Jesus' Passion and Death on the Cross, the focus now is in the original plan of God for us. God has always planned for us to live His life.
From the despair of death we have moved towards hope in life. So to correct a family member is to bring him back to Life. And to support one another in the group towards Christian perfection is to put true Life in the group. To condone, to be complacent however is to allow sin to corrupt a person and a community. The true cost of sin that one may win back life is not death but love, a love that expresses itself by looking out for one another, a love that binds the community together, a love in which Christ manifests Himself to us.