γίνεσθε δὲ εἰς ἀλλήλους χρηστοί εὔσπλαγχνοι χαριζόμενοι ἑαυτοῖς καθὼς καὶ ὁ θεὸς ἐν Χριστῷ ἐχαρίσατο ὑμῖν. But become kind to one another, tender-hearted, forgiving to each other, just as also God in Christ forgave you.
Instead of being angry, bitter, or vicious, Paul commands them to be kind to each other. Not only should they be kind, but they should also be tender-hearted or sympathetic, and they should also be forgiving with each other. Why? Just as God forgave them, so should they also forgive each other.
Note the textual variant here. The conjunction δὲ is not in a few manuscripts that have οὖν instead (F, G, and the original hand of D). Several manuscripts omit a conjunction altogether (Papyrus 46, B, Clement, and the original hand of 1739 to name a few). But the majority of the texts include δὲ (Papyrus 49, א, A, ψ, 33, Tertullian, and a manuscript of 1739). Since the conjunction has some of the earliest support, albeit not the earliest, and wide attestation (Western from א, Alexandrian from A, and Byzantine from F, G, and the majority text), we can legitimately consider it to be original. Additionally, this sentence stands in contrast to the previous one. The inclusion of δὲ fits the context and style. Therefore, we should consider it to be original.
But be kind to one another, sympathetic, forgiving each other, just as also God forgave you in Christ.
With God’s help we can release our anger, bitterness, and viciousness, but, because of God’s work, we can also be kind to each other and sympathetic. Most of all, instead of harboring anger and bitterness, we can forgive each other. Forgiveness is possible because God forgave us. We bear a responsibility to imitate God in this sense. We are to be constructive and not destructive with each other. Anger and bitterness can easily destroy, which is why we must let them go. Instead, we ought to be kind to each other, showing sympathy, and forgiving each other. When someone hurts you, do not retaliate, but instead, be kind and understanding, but, most of all, forgive the person. Those who have been forgiven by God necessarily forgive others.