Colour me whooshed. 
It’s tough being atheist and being a sincere well-wisher.
“Good luck!” (Pfft. Yeah, right. Luck shmuck. For all I know, you’ll get run over by a truck in five minutes.)
“Have a safe trip!” (Well, the odds are certainly in your favor, but it’s not like anyting I say is going to make a damn bit of difference if the engine falls of the plane, now, will it.)
“Everything’s going to be just fine!” (Yep. I’ll just snap my fingers, and hey presto, life is good. Don’t worry about unfortunate eventualities because…well, because I said so. Hey, I’ll feel better now, don’t you?)
I think “bless your heart” can also mean “GD you”- sorta a reverse twist.
However, I’m sure plenty of Texans use it the regular way also.
It means: “Ya’ dumb f**k/ dumb ass ect…”