Your last sentence demonstrates why some people have a need to argue with religious fanatics. Some people-- the OP, for example-- by necessity live in areas where decisions and opinions based on fundamentalism affect the lives of those who don’t. You can choose to not live in the south; great but not everyone can do that.
Arguing may not convert the fundie with whom one disagrees, but it might sway someone else, and at the least it sends the message that “not everyone agrees with you, and some people aren’t afraid to speak up.” Maybe the southern US might not be as bad if, perhaps, some science-minded folks spoke up to (or ran for) school boards and such, instead of just moving away.