I'm personally very supportive of the billboard. As a college student, it seems every other day I get handed flyers from campus religious groups, usually Christians. Christianity has its hands in pretty much every aspect of sociopolitical discourse in this country - from abortion to stem cell research to gay marriage to ... etc.
Essentially, I think that when they stop shoving their beliefs down our throats, we can stop giving them level-headed, thoughtful, and rational reasons to not believe. Because by that point they'll all be atheists.
Ouch. Alabama doesn't sound like the most atheist-friendly area. I'm surprised that teacher has any sort of degree; creationists are some of the dumbest people around.
Hope things get better for you :)
Oh yeah, it definitely gets better in college. I'm at UMD now and there's actually a pretty big atheist population here, hopefully you'll find some of us wherever you end up. The first campus Freethought Society meeting was so exciting ;)