I can understand your reasoning, but I would challenge your premise. Your premise is that the Devil actually won against God, which you base on the existence of Hell and evil.
This premise would assume that:
A. If God were all-knowing, he wouldn't create evil.
B. God is doing nothing
These are some issues that I have dealt with as I have journeyed back to faith. What I found in my answer is that:
A. Assuming that evil shouldn't exist is a statement about how humans believe the universe should run. Of course, humans would assume that because God is good, there should be no evil. How would you define "good" if that is the only option is "good". A higher ethic (in my opinion) is to choose good while evil exists (that whole "free choice" argument). This exists in all of the major religions.
B. God is doing nothing. As a person of faith, of course, I would say that God is actually doing a lot. The evidence depends on who you believe "God" is and what you believe "God" should or can do. If you don't believe in God, no amount of evidence will convince you. If you do believe in God, everything can be used to support it.
In short, evil either has to be part of an all-knowing God's plan or a mistake. Either way, all of us humans have to try to live together the best way we know how.