You're obviously talking about a character with +29 or more to his UMD check or we wouldn't even be having this conversation. Not rolling a 1 on any one of 168 UMD checks is highly unlikely. Heck, even with a +29 UMD check, there's still a chance of failure if, at any time during that week, the character is effected by a prayer, bestow curse, spell, fear effect (shaken gives a penalty to saves IIRC), or other effect that would reduce his skill check.
As for how I'd rule, if they made the 168 UMD checks, they'd get the wisdom bonus, and one level... that had to be a level of cleric to an evil god. (Although I might allow blackguard). If they didn't want that cleric level, they'd have to quit reading the book before aquiring the other benefits. And if they did want that level, they're pretty darn close to evil already.