Often we can see how bad things "work together for good" [Romanos 8:28]. The problem is that we can only glimpse this sometimes, in a limited number of cases. But why could it not be that God allowed evil because it will bring us all to a far greater glory and joy than we would have had otherwise? Isn`t it possible that the eventual glory and joy we will know will be infinitely greater than it would have been had there been no evil? What if that future world will somehow be greater for having once been broken and lost? If such is the case, that would truly mean the utter defeat of evil. Evil would not just be an obstacle to our beauty and bliss, but it will have only made it better. Evil would have accomplished the very opposite of what it intended.
How might that come about? At the simples level, we know that only if there is danger can there be courage. And apart from sin and evil, we would never have seen the courage of God, or the astonishing extent of His love, or the glory of a deity who lays aside His glory and goes to the cross. For us here in this life, the thought of God`s glory is rather remote and abstract. But we must realize that the most rapturous delights you have ever had- in the beauty of a landscape, or in the pleasure of food, or in the fulfillment of a loving embrace- are like drewdrops compared to the bottomless ocean of joy that it will be to see God face to face [1 John 3:1-3]. That is what we are in for, nothing else. And according to the Bible, that glorious beauty, and our enjoyment of it, has been immeasurably enchanced by Christ`s redemption of us from evil and death. We are told that the angels long to endlessly gaze into the gospel, into the wonder of what Jesus did in His incarnation and atonemen [1 Peter 1:12].
[Timothy Keller in "Walking with God through pain and suffering]