Talking to people works!
The growing group of non-religious students at my high school, near Atlanta, Georgia, just experienced something of a victory, and I wanted to share it with you all so as to combat the "common knowledge" that Christian conservatives (or anyone else, for that matter) cannot be reasoned with.
Exhibit A: I, a liberal atheist and huge Sagan, Dawkins, and science reader, started a math class only a year ago with my new friend, who was at the time a very Christian, very conservative, Reagan-worshiping, FOX "News" viewer (though to be fair, he was a big reader like me, which is what helped change him).
Being in an American math class, we didn't really have much to do, so we debated EVERY DAY FOR A YEAR (school year that is), despite the complaints of many within earshot who for some reason loathed the idea of people talking about religion and politics.
After a year of us bringing up our best arguments against each other's beliefs, he went from Baptist, to general Christian, to "All religions worship the same God!", to deist, to reading The God Delusion and saying "Wow, I can't believe I used to believe that garbage!" To be fair, he changed my views some as well, not much on religion, but on a few political issues that needn't be discussed here.
My point is that debate, not between public figures with huge audiences, but between reasonable individuals in a small and calm setting (and therefore without their status at stake) can be extremely constructive. As long as before you start the argument you make the ground rules clear (that nothing you say is personal, that you must do your best to avoid hyperbole, and that claims require sufficient evidence to support them, etc) you can keep the discussion from exploding or devolving into a waste of time.
Just throw in some concessions when they make a good point, don't give up if they don't understand one of yours, and understand that we are all humans, with limitations from our biology and environment for sure, but with the potential to change and become better.