Mysterium tremendum

Mysterium is used to describe that which is hidden and esoteric, and beyond our understanding. In religion one is often captivated by a feeling, or idea that is beyond understanding. The very idea of "perfection" in god is beyond understanding yet people are still captivated by that feeling. That feeling can come gently or strongly and it comes and goes, sometimes giving way to the profane. Even though the word has negative connotations, in can inspire very positive feelings.