Last night I was putting my son Daniel to bed and had just finished reading "The Prince's Poison Cup" (a children's book by R.C. Sproul) with him when he asked me two profound questions: "Why did God make people who sin? And why did God make Satan?" Through our discussion, it was clear that he knew that God is in complete control of everything and can do whatever he wants; he knew that God could have made a world where Satan did not exist and people did not sin. Given that, then why did he create a world that could go bad?
My initial answer (which bought me a little time) was to say, "That's a good question...I'm not really sure, but God has His purposes for everything." But upon further reflection, a passage came to mind that shed some light on the issue. In the book of Exodus, God is explaining why He didn't just wipe out the evil and oppressive nation of Egypt and their proud Pharaoh. He says in Exodus 9:16: "But I have raised you up for this very purpose, that I might show you my power and that my name might be proclaimed in all the earth."
God allowed evil to continue for a time in order that all nations might hear and see the power and glory of God. It was for a far greater good. So, God ordains sin and the very existence of Satan in order to display His glory throughout the earth.
(NOTE: let it be known that God's ordaining sin is not the same as His committing sin or being in any way responsible for the sinful actions of man...for example, God ordained that Judas would betray Christ, but Judas was fully responsible for his actions...see Matthew 26:24)
With all this in mind, I offered my son this response:
"If you never got sick, would you ever know how wonderful it is to be healed? If you never sinned, would you ever know what it is to be forgiven? God ordains sin so that we can experience His healing and forgiveness. We would never know anything of God's grace and mercy if we had never sinned.
And as for Satan: if there were no evil villains, would we ever know how powerful and just Superman is? Or how amazing Spiderman is? Without Satan, we would not see how great and just God is...especially in the end when He finally crushes Satan and all his demons!"
He seemed satisfied with those answers...at least for the moment.
For further study on this topic, I highly recommend John Piper's recent book Spectacular Sins and Their Global Purpose in the Glory of Christ. You can click here to download this book for free or listen to Piper's sermon series.