They kill the widow and the sojourner,
and murder the fatherless;
and they say, “The Lord does not see;
the God of Jacob does not perceive.”
This is more than just a complaint against the sins that people do. This is a cry for God to act. This is a plea for God's justice to right wrongs. This is a call for a holy God to judge wicked people where evil acts are destroying lives at every level. This destruction was evidenced in the way that most powerless people were treated.
In ancient Israel there were three classes of people at the bottom of the social structure: widows, orphans, and foreignors. And in this plea, the psalmist intercedes for all three groups who are being "killed" by oppression. Was murder really happening? Were the poorest people rounded up and executed? If we take the text at face value (and nothing else in the text is hyperbole) then we must say in some way that arrogant leaders were deliberately destroying the poor. Wicked actions were taking their innocent lives. The oppressors are called "dull" and "foolish" because their actions are in direct violation to God's clear scriptural commands that Israel care for the neediest among them (see Deuteronomy 10:18; 14:29; 24:17-19; and 27:19).
That this psalm of petition asking God to avenge the murder of the innocent was part of the worship hymnbook of Israel makes us a little uncomfortable today. I mean this song would not chart on CCM radio! But our societal evil will and MUST be judged. God cares for those who have no voice. He wants us to cry out for them and identify with their plight. And Christian faith that knows that Jesus died at the hands of oppressors must do the same. We are told to have a true religion that cares for widows and orphans. We cannot stay aloof from murderous injustices. And so when our society turns a blind eye to it, we must see it, cry out to God to find strength and justice, and demand that evil end.