This article answers the question why, if God exists, there are so many evil things in the world.
The answer is that the devil is the god of this world; he makes evil things happen because he is evil. The bible says that he is the god of this world and he doesn't want men to know the truth of God:
But even if our gospel is veiled, it is veiled to those who are perishing, whose minds the god of this age has blinded, who do not believe, lest the light of the gospel of the glory of Christ, who is the image of God, should shine on them. (2 Corinthians 4:3-4, NKJV).
When we are not on God's side, we are on the devil's one, even if we don't believe that he exists. The devil corrupts the entire world: "We know that we are of God, and the whole world lies under the sway of the wicked one" (1 John 5:19, NKJV).
Jesus defeated the devil at the cross, he took back the keys of Death and Hades from the devil.
The devil will be thrown into the lake of fire with all his demons (Revelation 20:10).
Jesus gives us eternal life (1 John 5:9-13). John the Baptist said:
"He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him." (John 3:36, NKJV).
Jesus Christ has the victory over the devil and He gives us the victory.
Let us believe in Jesus Christ unto everlasting life.