Why should we be concerned about the vulnerable ones? It is because God is concerned about them. Consider the following texts:
He executes justice [mishpat] for the oppressed and gives food to the hungry. The LORD sets prisoners free, the LORD gives sight to the blind, he lifts up those who are bowed down, the LORD loves those who live justly. The LORD watches over the immigrant and sustains the fatherless and the widow, but he frustrates the ways of the wicked. Psalm 146:7-9
The LORD your God . . . defends the cause [mishpat ] of the fatherless and the widow, and loves the immigrant, giving him food and clothing. Deuteronomy 10:17-18
It is striking to see how often God is introduced as the defender of these vulnerable groups. Don’t miss the significance of this. When people ask me, ‘How do you want to be introduced?’ I usually propose they say, ‘This is Tim Keller, minister at Redeemer Presbyterian Church in New York City.’ Of course I am many other things, but that is the main thing I spend my time doing in public life. Realize, then, how significant it is that the Biblical writers introduce God as ‘a father to the fatherless, a defender of widows’ (Psalm 68:4-5). This is one of the main things he does in the world. He identifies with the powerless, he takes up their cause.
– Tim Keller