The only thing God can't do is commit evil. God can't lie, for example, nor can He act unjustly or selfishly. The Bible says, "He is the Rock, his works are perfect, and all his ways are just. A faithful God who does no wrong, upright and just is he" (Deuteronomy 32:4).
Why, then, is there so much evil in the world? That isn't an easy question to answer; I have pondered it for many years, and I still don't know the full answer. But I do know this: God is real—but so is Satan, and the evil we see all around us comes from him, not from God. It also comes from the sin and rebellion of our own hearts. The Bible says, "God cannot be tempted by evil, nor does he tempt anyone; but each one is tempted when, by his own evil desire, he is dragged away and enticed" (James 1:13-14).
Someday the warfare between good and evil—between God and Satan—will be over, and Christ will emerge victorious. In fact, the decisive battle has already been fought. It happened when Jesus Christ conquered sin and death and Hell by dying on the cross for our sins and then coming back to life by God's power.
In the meantime, God calls us to be faithful to Himself, and never give in to evil or sin. Is your hope in Christ? And are you seeking to live for Him every day? Don't give in to despair, but set your sights on Christ's victory.