On American Idol, Simon has made suggestions to the contestants that they need to be more selfish or conceited (his way of saying that they need more self confidence). To have "self-confidence" you need a good sense of self worth, but not to the point of selfishness or conceit! I believe that in order to perform music well, especially music of a sacred nature, you must become totally
self-unconscious – you’ve got to loose yourself in the music. A great music performance, whether sacred or secular, involves that spiritual portion of the brain (there was a scientific study on this - google it). This is what enables you to put "soul" into your music. Our brain appears designed so that in this state of unselfishness, produced during such activities as prayer or praise, we become more sensitive and connected to that inner voice - God speaking through our conscience. Conversely when you become too self conscious you experience stage fright thus sabotaging the full musical experience and the connection. Remember that it is our selfishness (aka sin) that separates us from God, and each other.