1. You are stupid.
2. You poor dear.

Almost everyone knows Southern women drop this phrase constantly. But it might not mean what you think it means. In reality, the phrase has little to do with religion and more to do with a passive-aggressive way to call you an idiot. Depending on your inflection, saying “bless your heart” can sting worse than any insult or be used to express sympathy. It depends on the infliction and context it is used in. The southern US has a vocabulary uniquely its own, and I would love to teach more sayings and expressions. :D