The reason God is not be the author of sin and evil is that he limits his power in relation to creation. By his own choice he is not, in the inimitable words of Baptist theologian E. Frank Tupper, a "do anything, anytime, anywhere kind of God." He could be, because he is omnipotent, but he chooses not to be that kind of God. Why? For the sake of having real, rather than imaginary, relations with human persons…
I don’t comment on unattributed quotes where the poster doesn’t have the courtesy of explaining who is speaking.
But to help you out and show you it is possible to do so, here is the unattributed link which you are excerpting...
http://www.mercy-church.org/wordpress/?p=3061