Is God responsible for evil?

Is God responsible for evil?

Well, yes, in so far as God is responsible for everything, in so far as He has the knowledge and power to stop evil.

But is evil God's will?

That is a much more interesting question. Evil, human evil at least*, is mainly God's responsibility in so far as he gave us free will. God lets evil exist. We cannot deny that. Blaming Satan or demons (not that I believe in those literally) just pushes the problem back another level because if they exist, it is also by God's leave.

So evil exists by God's leave, but is it his will?

As with all questions of this nature, we cannot know. For all that we know, God could have created us because he likes to see suffering. But I believe is that evil is not God's will. Evil is God's concession to the reality that growth cannot happen in a static universe, growth cannot happen without suffering. Ultimately, God wants us to grow. Thus, God lets us be and suffer from evil.

Is there more suffering than is necessary for growth? Probably. But if God were to hold us back so that we experienced just enough evil then we would not be growing.

* Natural evils, or rather, the natural events we call evil, fall under a different discussion.