Christians: how would you respond to this statement?

Now i've heard this quote several times, and while i'm not the smartest person but i think the answer lies in the question is he both able and willing? The answer to both is yes. And the question posed, whence cometh evil, has been one argued over for centuries. In short, evil is the absence of God. What causes God to be absent? Sin, rejection of him, etc. The thing is man has free will and God will not violate that free will. Again, i'm not the smartest person, i'm sure there is a better answer for it, but that's my take on it.