Many people have understandable anguish over the suffering in the world. This is probably the most effective argument of anti-Christians. But it is still invalid.
To an atheist, we could ask: ‘What is your criterion for judging whether something is good or bad? Since you reject God’s transcendent moral standard, all you have are your own feelings. Why should we accept the feelings of an admittedly fallible human being?’
God created a perfect world; the free choice of Adam to turn his back on Him is the ultimate cause of all the suffering. The efficient cause of specific suffering is the free evil choice of moral agents. However, Scriptures are clear that those who suffer the most are not necessarily the most sinful (e.g. John 9:1–3).