I have heard so many times this statement:

You must be a good testimony to other
OR
Don't stumble others.

I just find that this statement is an exucse for people to practice religion in a worldly sense. I just do not really feel that people who made these statement really mean what they say. I think what they say is, "I got to earn it for God." or "See how superior I am compared to you, O non-Christians"