Keller analogizes many Christians to a pop machine. You've put the pennies in, but they haven't dropped, so you're not getting anything out (hence my new March masthead). If you're curious, listen to THIS talk about smashing idols - approx. 38 mins.
I strongly recommend clicking here & downloading (for free) the sermon called "The True Older Brother" - approx. 32 mins.
After being a "Christian" for practically 20 years, trying to be good enough and trying to stop sinning... my pennies are finally starting to drop.