Actually...here's my .02 worth...From a strictly professional point of view, many times in a manager / subordinate relationship, it's a good idea not to be overly familiar, cultivating after hours relationships with employees. The reason isn't that you are not expected to be human, but rather, it can engender feelings of entitlement and special treatment in the subordinate. They also, in social settings, run off at the mouth about things they really shouldn't. Then the question isn't just "Should I give this girl religious advice?" but "How do I now treat this employee who is or at least thinks she is closer to me than her peers?"
It's a sticky situation, that's for sure. I, too, would advise treading very carefully here.
Ern