Evil Does (not) Exist

Does evil exist? This is the question I had been asking for so long until I read The Confession and The City of God of St. Agustine of Hippo (Aljazair nowadays). The question weather evil exists or not is crucial regarding to our faith in God. These simple questions might trigger you and me why such a question is important: If there is a benevolent and omnipotent God, why there is evil? Why there are afllictions throughout the earth if God is capable of doing anything? Is our God is a careless divine being? If He loves human being and all the creatures, why then all the corrupting things should happen? What God has done if He truly exists, and benevolent, and omnipotent?