And just as you want men to do to you, you also do to them likewise. But if you love those who love you, what credit is that to you? For even sinners love those who love them. And if you do good to those who do good to you, what credit is that to you? For even sinners do the same. And if you lend to those from whom you hope to receive back, what credit is that to you? For even sinners lend to sinners to receive as much back. But love your enemies, do good, and lend, hoping for nothing in return; and your reward will be great, and you will be sons of the Most High. For He is kind to the unthankful and evil. Therefore be merciful, just as your Father also is merciful. (Luke 6:31-36)
Treat others as you want to be treated by them. This is how we live by love – not by reacting towards others, but by initiating the behavior we choose as love in each encounter. St Hesychios the Presbyter says:
If you do not want to suffer evil, do not inflict it, since the suffering of it inevitably follows its infliction. ‘For whatever a man sows, he will also reap‘ (Galatians 6:7). Reaping unwillingly the wickedness we deliberately sow, we should marvel at God’s justice. (THE PHILOKALIA Vol 1, p 172)
St Hesychios links our choice to do unto others as we want to be treated with what we sow in the world – good or evil. God’s justice is to allow each of us in the end to experience our behavior towards others. Judgment Day will be our receiving back what we have sown in this life time. Good reason to treat others with love, kindness, hope, and mercy. St John of Kronstadt writes:
Do not let the Devil sow enmity and malice in your heart against your neighbor; do not let these feelings nestle in any way in your heart; otherwise your malice, even if not expressed in words but shown only in your glance, may infect through sight the soul of your brother also (for nothing is so infectious as malice, it easily infects especially those, who have in their hearts an abundance of unslumbering malice), and fans the spark of evil in them into a whole flame. Be watchful: ‘with what measure ye mete, it shall be measured to you again‘ (Matthew 7:2). ‘For, nothing is secret, that shall not be made manifest; neither anything hid, that shall not be known and come abroad‘ (Luke 8:17). (MY LIFE IN CHRIST, p 198)
We are not to treat others as they treat us (retributive justice), as that is allowing them to control our behavior. We end up simply reacting towards others, while love shows us how to act towards others — treat them as we ourselves want to be treated by them. In others words, we are to be examples to them. Our behavior is not to be governed by them, but by love which is something we have to choose.