suffering

Dear scholars, as-salamu `alaykum. I tried to call a colleague of mine to belief in Allah and to Islam. He said that his main barrier to belief in the existence of God was that totally innocent children go through pain and suffering on earth, and that he could not understand why, if God existed, this could be allowed to happen. I gave it some thought, and came up with an answer, but would like your comments too before communicating with him again.

I was wondering if you could possibly help me resolve some conflicting issues. If God is All-Powerful, He must be able to prevent evil. If God is All-Good, He must want to prevent evil. But evil and suffering exist. How is it possible for God to be both All-Powerful and All-Good and still allow a world in which evil and su ffering exist? I would greatly appreciate a response.