"Many books, including some of the earlier Church Doctors, hold the view that evil is only the absence of good, for a Scholastic reason."
Figures those guys would be behind such a notion.
"If evil is something in and of itself, then God had to create it, so God is the author of evil. Which leads to all sorts of dark places and a more fatalistic view of creation and God. To view evil as the something created by God, it would half to be "good" since everything God creates is good. So it is easier to define evil as the absence of good, then to say it is a real "positive" (not sure that is the right term, but I mean a real force) force."
God created Satan. It doesn't follow however that God therefore created evil. He created us in the image and likeness of Himself, with free will among other attributes, but it doesn't follow that because Adam fell, He is therefore the author of the Sin of Adam or any other sin we have committed since then. What was their thinking?
God created Satan good. But when Satan willed to become evil, he was not creating some new phenomenon in the cosmos. Rather, Satan took his originally good nature and essentially threw it in the garbage. He denied himself every good attribute that God gave him and sabotaged an already existing good by not cooperating with it. That was all that was in his power to do--because he was creature and not Creator.
It is in that sense that we say that evil is a privation of a good. And it doesn't come from a mistranslation of the Our Father, it is rooted, as redgolum said, in the absolute certainty that God cannot create evil against His very nature. And creatures cannot create at all, so that evil must be (rather than a dualist force counterbalancing the good of God), a "blocking of the flow" of God's good graces.
(No theologian I, so take my thoughts for what they are worth :)