Food for Thought from the Screwtape Letters

I'm reading C.S. Lewis' The Screwtape Letters (again), and the following excerpt grabbed my attention: "Once you have made the World an end, and faith a means, you have almost won your man, and it makes very little difference what kind of worldly end he is pursuing."
C.S. Lewis, The Screwtape Letters 34-35 (1996). 

"Once you have made the word an end, and faith a means..." How many Christians today - perhaps unknowingly - make faith a means to having the World? "Indeed, I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord." Philippians 3:8 (English Standard). I'm certainly convicted and guilty. 
"Wretched man that I am! Who will deliver me from this body of death? Thanks be to God through Jesus Christ our Lord! So then, I myself serve the law of God with my mind, but with my flesh I serve the law of sin." Romans 7:24-25 (English Standard).