In this excerpt from his teaching series The Parables of Jesus, R.C. Sproul distinguishes mercy from injustice.
Transcript
Now I'm going to draw a little circle here on the board. And this circle represents the concept of justice. Now everything outside this circle can be put in the negative category of non-justice—that which is not justice, but is non-justice. For purposes of illustration, I'm going to put a little boundary there, put another circle out here, and everything in this circle out here is non-justice. But there's more than one kind of non-justice. Here we have a non-justice that is injustice, and that is unrighteous and evil. Right?
Over here we have grace, or mercy. Is there anything evil about grace? Of course not. Is there anything wicked about God's being merciful? No. When God is gracious He does not commit an injustice; He does commit a non-justice.
So what happens is for those whom He elects and saves sovereignly, receive His grace. Those who do not receive His grace receive what? His justice; exactly what they deserve. Now, do we really believe that God is sovereign in His grace? Paul goes on to answer this question, is there unrighteousness in God?—God forbid, by no means!
Did not God say to Moses, "I will have mercy on whom I will have mercy"? God sovereignly has the right to be generous in His mercy to one without being required to give it to the other.
