A third way to discern idols works best for those
who have professed a faith in God. You may regularly go to a place of worship. You may have a full, devout
 set of doctrinal beliefs. You may be trying very hard 
to believe and obey God. However, what is your real,
daily functional salvation? What are you really living
 for, what is your real – not your professed – god? A 
good way to discern this is how you respond to un-answered prayers and frustrated hopes. If you ask for
 something that you don’t get, you may become sad
 and disappointed. Then you go on. Hey, life’s not over.
  Those are not your functional masters. But when you
 pray and work for something and you don’t get it and
 you respond with explosive anger or deep despair, then 
you may have found your real god.  (Keller, Counterfeit Gods, p. 169)