We often see justice and mercy as diametrically opposed. Justice is served when the proper price is paid. Mercy is compassion and forgiveness, usually involving a withholding of a due penalty. So how can both justice and mercy be perfectly given in salvation?
How does salvation involve both justice and mercy?
Let's first begin by acknowledging that God is perfectly just and also merciful. We can see these attributes of God on display throughout the Bible. For example, Psalm 103:8 declares, "The Lord is merciful and gracious, slow to anger and abounding in steadfast love." Isaiah 30:18 says, "Therefore the Lord waits to be gracious to you, and therefore he exalts himself to show mercy to you. For the Lord is a God of justice; blessed are all those who wait for him." Second Peter 3:8–10 says, "But do not overlook this one fact, beloved, that with the Lord one day is as a thousand years, and a thousand years as one day. The Lord is not slow to fulfill his promise as some count slowness, but is patient toward you, not wishing that any should perish, but that all should reach repentance. But the day of the Lord will come like a thief, and then the heavens will pass away with a roar, and the heavenly bodies will be burned up and dissolved, and the earth and the works that are done on it will be exposed." God does, and will, judge sin. He also graciously, patiently, and compassionately extends mercy. Neither His justice or mercy is given at the expense of the other. This is because of the reality of Jesus.
Second Corinthians 5:19–21 says, "In Christ God was reconciling the world to himself, not counting their trespasses against them, and entrusting to us the message of reconciliation. … For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God." The price for sin is death (Romans 6:23). Jesus paid this on our behalf. Because He is both fully human and fully God, His sacrifice could be applied to us. He lived a perfect human life, thus had no need to pay for sin Himself. As God, He is infinite, meaning His sacrifice can cover a multitude of offenses. In short, God had mercy on us because He enacted justice on Jesus.
The amazing thing is that Jesus willingly did this. John 3:16–17 says, "For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him." In John 17, Jesus prays for His followers, demonstrating His desire that they be unified and also eventually be with Him and able to see His glory. God loves people enough that He chose to create us, knowing full well that we would sin and be in need of redemption. In His mercy, He provided a way for that redemption. In His justice, He, Himself, paid the price for sin.
Romans 3:21–26 shows mercy and justice at work together: "But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it—the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: for all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith. This was to show God's righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus."
What is the difference between mercy and grace?
How is Jesus' sacrifice propitiation for our sins?
Why did Jesus have to die?
What is the meaning of substitutionary atonement?
What is the significance of "sola gratia"?
Truth about Salvation