In parts of the Bible it has God saying things like, basicaly, it is "I that takes you high, and I that makes you low" a completely over simplised version but, I think check the Psalms for some of the snipets I'm talking about.
I believe the Bible(Jesus) says that God is Truth, I've just finished the autobiography of St. Teresa of Avila, and she makes this completely clear, that God is absolute Truth(with a capital T

) so if Satan is the opposite, "The Adversary" which is the name it/he was given in the Old Testement, it is delusion. As you can see from this it is starting to take on a guise similar to Buddhism or Hinduism.
If God is the only one doing both good and bad to us, then Satan has to be the instrument, even if Satan was completely evil in itself, considering a polar type creation, there still are redeming factors in the effects that this instrument can have, and in the fact that God is using Satan, and the fact that Satan is a creation of God (which sound like the same things but are a little different in this context at least.) Perhaps Satan is truly evil, but only as evil as God will let him be, though remaining the ultimate evil, or definition of that. Assuming any of this is true of course.
As for God's omniscience, how can one come to any real conclusions about that? If everything exists within God, as is the conlcusion of some Christians as also people of other religions, then unless God chose to somehow not be aweare of somethings, perhaps He's doing that through us, then He would be omniscient, basicaly just by the definition of God that we are usualy given. Which is kind of funny and kind of sad. Though it should be noted that usualy these ideas are based on real, if not true experiences that people have had, and are not just thought up, as I'm doing now.
I'm of the opinion that you shouldn't worry to much about these things utill you see them for yourself, because they'll only get in the way of you seeing them for yourself. Afterwards draw your conclusions, otherwise, unless nessecary, quitely let other go about whatever bussiness they wish.
Bullshit lesson concluded.