8 And the word of the Lord came to Zechariah, saying, 9 “Thus says the Lord of hosts, Render true judgments, show kindness and mercy to one another, 10 do not oppress the widow, the fatherless, the sojourner, or the poor, and let none of you devise evil against another in your heart.”
He has told you, O man, what is good; and what does the Lord require of you but to do justice, and to love kindness, and to walk humbly with your God?
Kindness is part of the fruit of the Spirit. It is more than being nice. God wants us to do things for others without expectations. In the verse from Zechariah, the Lord points out to us groups of people who could not possibly reciprocate. He asks us to go out of our way for those that others may ignore. How you treat others matters to God, and it matters to other people. God demonstrated the ultimate kindness by sending his only Son to die on the cross for our sins. We deserve to be punished for our sins, but God gave us Jesus. If we believe Jesus is the Son of God and our savior, then we will NOT be punished. God demonstrates kindness in this way, He does not excuse our sin, but provided the atonement for it. We can demonstrate this fruit, not by excusing the sin or bad behavior of others, but by loving people in spite of themselves (and ourselves).
Remember the words of the apostle Paul in Romans 12:
19 Beloved, never avenge yourselves, but leave it[i] to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.” 20 To the contrary, “if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head.” 21 Do not be overcome by evil, but overcome evil with good.