Text (US+errata): 1/1. ; When ~this~ enters the battlefield, destroy target enchantment. [Oracle 2009/07/08]
If there is an enchantment in play just after it comes into play, you must destroy one. If not, then the "comes into play" ability just doesn't do anything. [Urza's FAQ 1998/10/05]
Note - This card was creature type "Cleric" until Oracle 2007/10/01, when it became "Human Monk Cleric".