There is definitely a demonic representation in C.S. Lewis' allegorical masterpiece, but I have never heard someone question the Godly heart and voice of the literature. For all of its fable, Narnia is a mirror image of our reality, a place controlled by the prince of the power of the air, much like our fallen earthly world. And of course, just as Aslan himself is a mere representation of the Father's son, the witch is simply the embodied visage of the evil one. And herein lies the definitive crux of The Lion, the Witch, and the Wardrobe as Aslan's sacrificial atonement gives way to one of the most beautiful lines, "...when a willing victim who had committed no treachery was killed in a traitor's stead, the Table would crack and Death itself would start working backwards." For us in the really real world, Jesus Christ rescues believers from eternal separation from God through deeper magic founded in the Godhead before the beginning, praise God! If you don't categorize God's supernatural, omniscient, omnipresent Spirit as the deepest magic known in existence, then you're clearly hung up on the "evil" connotations associated with the word, but this merely makes it a pejorative of sorts. God's pure holiness--His light--is our magic! I pray, I believe, I follow the master of the miraculous!
I've never considered Narnia to be masquerading as light. There are some ideas purported by Lewis that are unique to his faith-stance, but these are by no means wolves employed to deceive. Of course, if you're referring to the Hollywood film...well I have no idea what licenses they've taken or what pagan systems they're exalting in the process.