One man who claims to be a Christian calls into question God's sovereignty. Another man who claims to be an atheist calls upon human reasoning and asks for definitions of "evil" and "good". Another man who claims to be a Christian takes the orthodox route and attempts to explain what church fathers have attempted to explain for centuries. Here is an excerpt from one of the comments by Klay Aspinwall, a former student of Union University.
I would say that God decreed to allow the Fall that He might also decree to provide redemption. In this drama of fall-and-redemption the glorious attributes of God are most clearly seen in eternity. His righteousness and justice in the destruction of evil and punishment of wrong.
His grace, mercy, and love in the salvation of many repentant sinners.A pristine world that had never known struggle, sin, evil, and sorrow would not be a completely "perfect" world...
You can read a lot more here (especially in the comments).