In his book Authentic Christianity, Ray Steadman talks about the "veils" Christians wear--those things we hide behind to disguise what is really going on inside.
Here's one veil he discusses:
Self-righteousness is a particularly noxious form of Christian pride. It seizes upon some biblical standard of conduct and takes pride in own ability to measure up externally while conveniently overlooking any failure of the inner life to conform. The end result is a smug, patronizing, and even nasty attitude toward anyone who does not meet the standard. Self-righteousness is also the sin of the person who nags another, for the nagger is focusing on a single point of conduct and ignores the areas in his or her own lifewhere a similar failure is occuring.