1 level of cleric does not help with UMD, noob!
1 level of cleric lets you use some healing wands/scrolls without a UMD check, and 1 level ranger, paladin, favored soul, or bard does the same thing. i.e. classes using a wand version of a spell that they have on their spell list can use that wand without a UMD check, even if they're too low level to be able to cast that spell.
A rogue should be putting max ranks into UMD. This is so you can wear RR items and use high level divine scrolls (heal, raise dead), arcane scrolls (teleport, greater teleport, greater heroism, displacement), and arcane wands (blur, shield). All these things will use a UMD check even if you have 1 cleric level.