annoying christians

At work, there are these customers who come in and want every sort of deal they can get. They try to get things for half price when they're not supposed to be, they try to take the tags off and get me to give them a 'good' price. It bugs me. We're already the cheapest place in town for clothes, and what little money we make past paying bills goes to help charity. What's the deal? And, what bugs me most is that the people who try to get the most deals and break the most rules are christians. Or at least, church-goers. It's so annoying. Don't they realize that if they're claiming to be christians, they should be willing to give more to help out these needy people? Some of the customers are even pastors who wear flashy clothes and jewelry, and ride in nice cars. Gar! It bugs me to no end. Why can't these people get it!? And yet I still treat them fairly, giving them the same discounts that all the other customers get. Greet them with a smile when they enter the store. I don't want to, though.