What kind is it?
"Blessed be the Lord: for He hath shewed me His marvellous kindness..." (Psalm 31:21)
That's the way God is all the time. If we forget it or don't feel it, the fault lies with us. "Love is kind" (1 Corinthians 13:3) and "God is love" (1 John 4:8). One way to appropriate and to feel the kindness of God is to be that way ourselves, toward others. Don't worry about reciprocation or repayment. "I will repay" says God (Romans 12:19). Of course, He's talking about justice and vengeance and such, same idea. Paul says to "Owe no [one] any thing, but to love one another: for he (and she) that loveth another hath fulfilled the law." (Romans 13:8)
Kindness towards others, especially strangers, can be difficult when we don't see that God is kind towards us. If God is little more than an afterthought, or just someone that you go to when times are tough and the world is unkind, then we're not responding correctly to Him or to anyone else. "Follow peace with all men, and holiness, without which no man shall see the Lord." (Hebrews 12:14)
Whenever someone levels criticism at God for allowing a disastrous event to occur, I always wonder. I wonder where they were when (presumably) God showed them kindness. A smile from a stranger. Someone stopping for you and holding up traffic so you could cross the street. Free extra mushrooms for a mushroom-swiss burger (actually happened recently). The little things. Small graces. Gifts, all. The kindness of God shown through the hands and faces and hearts of people. This is the sunshine of God's love. This is where we should be storing up the kindness shown to us so we can in turn give it out. Kindness disarms and alarms. Motives are questioned (as they should be). "Why would someone I don't even know be kind to me?" Maybe God's trying to soften your heart. Perhaps there's someone that you blessed in the past and now you're reaping the fruits of that act of kindness. Either way, don't waste it. It came from God. "Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning." (James 1:17) If Jesus dying for the sin of the world, paying the ultimate price, is not kindness, then nothing is. Dispute all you want, God's hand on your head while you swing your fists...
How could God continue to be kind to a world that continues to dismiss, disrespect, disavow Him? Well, for starters, He's "not willing that any should perish" (2 Peter 3:9). I challenge you (if you haven't already) to lay down your unbelief, "the sin that doth so easily beset [you]" (Hebrews 12:1) and take God at His word.
Look at this verse. "But without faith it is impossible to please Him: for he (and she) that cometh to God must believe that He is..." (Hebrews 11:6) Is what? Well, "is", as in existent. But also all the things that the Bible says He is. Loving. Patient. Merciful. Caring. And Kind. The rest of the verse reads: ...and that He is a rewarder of them that diligently seek Him." Gotta belive that too.
"What shall I render to the Lord for all His benefits toward me?" (Psalm 116:12)
"Now therefore, I pray you, swear unto me by the Lord, since I have shewed you kindness, that ye will also shew kindness..." (Joshua 2:12)