The phrase rich in mercy is found in Ephesians 2:4 as part of a passage contrasting the condition of believers before they came to Christ and their state after responding to His call. In order to understand what it means that God is rich in mercy, we need to consider the context of the passage:
“And you were dead in the trespasses and sins in which you once walked, following the course of this world, following the prince of the power of the air . . . carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind. But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved—and raised us up with him and seated us with him in the heavenly places in Christ Jesus, so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus” (Ephesians 2:1–7, ESV, emphasis added).
In this passage, Paul first describes humanity’s deplorable condition in rebellion against God’s rich mercy. We were not only sinful, but we were “dead” in our sins. In other words, because of the sin nature that controls us, we were doomed to an eternity without God and without life (Romans 6:23). We deserved God’s wrath, and we could do nothing to save ourselves. Then comes the “but,” and the focus of the passage shifts to God’s mercy, love, grace, and kindness.
The phrase rich in mercy is a counterbalance to the description of humanity being rich in sin. Only a God rich in mercy would conceive a plan to save and redeem such wicked creatures. Mercy is compassion or forgiveness extended to someone who deserves punishment or harm. Mercy is undeserved pardon. Mercy is the only explanation for Christ’s great sacrifice on our behalf (2 Corinthians 5:21).
People can show mercy to one another on a limited, human basis. But our offenses against God were so heinous, so unforgivable, that His forgiveness shows Him to be more than merciful—He is rich in mercy. A God rich in mercy “demonstrates his own love for us in this: While we were still sinners, Christ died for us” (Romans 5:8). Before we cared or knew Him, God had already extended mercy toward us. First Peter 1:3 counters any tendency to believe that our salvation is due to some merit within ourselves: “Praise be to the God and Father of our Lord Jesus Christ! In his great mercy he has given us new birth into a living hope through the resurrection of Jesus Christ from the dead.”
God’s mercies continue after salvation as He offers His redeemed children forgiveness when we sin (1 John 1:9). Because He is rich in mercy, His mercies never end. They are “new every morning” (Lamentations 3:23). We never have to fear that one day God will get fed up and stop His patient working in our lives (2 Peter 3:9). We never need to worry that we have “used up” our portion of grace and kindness because our God is rich in mercy.