What is theodicy?

from the old testament

• Joseph realized God’s hand at work within the evil circumstances in which his brothers had placed him: “As for you, you meant evil against me, but God meant it for good, to bring it about that many people should be kept alive, as they are today” (Genesis 50:20).
• The psalmist wrote, "Our God is in the heavens; he does all that he pleases" (Psalm 115:3). Atheists often point to the evil in the world and say that an all-good, all-powerful God cannot exist because if He did, He would stop the evil. But the Bible teaches that God is all powerful.
• God permitting evil is often to reveal Himself to the world. In other words, God has a purpose for permitting evil. As His ways are higher than ours, we cannot claim He has no purpose in allowing evil for a time. The writer of Proverbs simply puts it like this: "The LORD has made everything for its purpose, even the wicked for the day of trouble" (Proverbs 16:4).
• The prophet Jeremiah recognized God’s power: "Ah, Lord God! It is you who have made the heavens and the earth by your great power and by your outstretched arm! Nothing is too hard for you" (Jeremiah 32:17).

from the new testament

• Jesus affirmed God’s omnipotence: "With man this is impossible, but with God all things are possible." (Matthew 19:26).
• God’s goodness and love are attested to in the Scriptures (Mark 10:18; 1 John 4:8). We can infer, then, that even the evil He permits for a time has an overall loving purpose to it.
• God’s glory is often manifested through the contrast of His goodness with our unrighteousness. Scripture confirms this when it says, "But if our unrighteousness serves to show the righteousness of God, what shall we say?" (Romans 3:5).
• John 9 records Jesus and His followers encountering a man blind from birth. His disciples ask Him, “‘Rabbi, who sinned, this man or his parents, that he was born blind?’ Jesus answered, ‘It was not that this man sinned, or his parents, but that the works of God might be displayed in him.’” (vv. 2-3). People often believe in God when they see evidence of His glory, manifested through His works. Salvation for eternity, on balance, offers more good than whatever physical ailment we might undergo on this earth.
• Sin and evil also showcase God's love, which Paul describes in the fifth chapter of Romans: "but God shows his love for us in that while we were still sinners, Christ died for us" (Romans 5:8). God's love is on display in all its beauty because of sin and Christ's act of mercy for sinners. Again, without evil/sin, such a thing could not be clearly manifested.
• The Lord will one day fully destroy evil after using it for His purpose. The writer of Revelation says one day God will "wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away" (Revelation 21:4).

implications for today

“Can God create a rock so heavy that He can’t lift it?” This and other gotcha questions are word games that online atheists use to stump Christians. (The answer, by the way, is that God can do all that is logically doable. A “rock so heavy that God can’t lift it” can’t logically exist).

But believers cannot be stumped if they’re rooted in Scripture. The Bible indicates that there are some things God cannot do: He cannot die (Psalm 90:2; 1 Timothy 6:16) and He cannot lie (Titus 1:2; Hebrews 6:18). These are not limitations of God; they’re manifestations of His perfection. His nature is perfect and holy. Scripture attests to God being all-powerful, all-knowing, and all-loving.

Such debates about God’s nature are called theodicy. But Christians have logic and truth on our side: Atheists are railing against a God they supposedly do not believe in, using a moral standard that has no grounding in their materialistic worldview.

This can be head-scratching until we remember Jesus’ explanation for why people reject truth: “And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil” (John 3:19). For God to remove all evil He would have to do away with our own free will.