The widow should have kept her two mites!

Luke 20:45-21:4

One of the most famous stories in the bible about giving is that of the widow's two mites. True, she was sincere and sacrificial. But why is this story included in the bible? Does it serve as a pattern for giving? I think not. In fact, the context makes its clear that she serves as an example of someone who had been completely taken advantage of!