“The metaphors of turning the other cheek, walking the extra mile, surrendering your coat, and adding the cloak are explained in Matthew 5:44: ‘But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you.’
The idea is that evil must be repaid with good, curses with blessing, hatred with love, sin with forgiveness, misery with compassion.
God acts this way, too (Matt. 5:45-48).
Once more, that is not apathy, no Stoic passivity, no condoning the enemy’s behavior. On the contrary, Jesus rebukes His enemies and pronounces woe upon the Pharisees. But while He is reprimanding the sin, He is loving and blessing the enemy.
Indeed, He commands us to forgive those who wrong us as often as seventy times seven– that is to say, countless times, again and again (Matt. 18:21-34).
The Pharisees said that one must forgive three times. Peter boldly says: Isn’t seven times enough?
But Jesus will have nothing to do with numbers or calculations here. The Christian should be an inexhaustible source of forgiveness.
After all, Christians need forgiveness themselves (Matt. 18:33).
Certain evidence that we love our enemies is when we pray for them in all sincerity. Righteous anger is certainly permissible and obligatory, but it must be an anger without sin, not long-lasting, and not rising rashly (Eph. 4:26-27; Ps. 4:4; 37:8).
‘The anger of man does not produce the righteousness of God’ (James 1:20; cf. Col. 3:8; Titus 1:7). And vengeance is never fitting; it belongs to God (Deut. 32:35).
Love thinks no evil (1 Cor. 13) and covers a multitude of sins (1 Peter 4:8).”
–Herman Bavinck, Reformed Ethics, Volume 2: The Duties of the Christian Life, Ed. John Bolt (Grand Rapids, MI: Baker, 2021), 2: 439-440.