This is what is often known as "The Beginner's Verse" because the first words are often taught to children in the Beginner Classes of most Sunday Schools. "Be kind to one another." Elementary. Everybody knows this. You can even still quote it since you first memorized it over 50, 60, or even 70 years ago!! That's nice. Do you practice it?
One of the hallmarks of a genuine Christian is their kindness. It clearly is one aspect of the Fruit of the Spirit in Galatians 5. It sets believers apart from this self-centered and selfish society we live in. And not only kindness. Being "tenderhearted" goes with it. Having a tender heart toward those who need mercy, comfort, and understanding, especially when they fail. And what else is here? FORGIVENESS! The kind of forgiveness that comes when we realize that we've needed forgiveness for our many sins! Its forgiveness as in "...forgive us our trespasses as we forgive those who trespass against us..." And you remember what Christ said after that, "If you forgive those who sin against you, your heavenly Father will forgive you. but if you refuse to forgive others, your Father will not forgive your sins." Matthew 6:14,15 NLT.
Paul reminds us of Christ's forgiveness. We should be as eager to forgive others as we were eager to ask Christ for forgiveness when we needed it.
Now, consider Galatians 6:1 about helping a "fallen believer." Can you not see that Ephesians 4:32 is the way to fulfill the restoration process of restoring a sinning Christian? Kindness, tenderness, and forgiveness - just what a fallen Christian needs!