David,
I've found nothing helps to dissolve fears faster than paying attention to them and not shirking away. One way to do this is to sit in a quiet room for a good amount of time and just get in tune with your mind and body (meditation, if you will). It's also possible to do this via journaling (and makes for interesting reading later). When journaling I generally write a dialog with the fear, ask it questions, and see how it responds. I've found it's fairly easy to drill down to root causes this way.
I wish I'd found this out years ago, it would have saved me a lot of time I wasted trying to hide from fear and anxiety with entertainment and other sensory overloads.
Using these methods I've been able to understand and resolve anxieties and fear sitting in the pit of my stomach that I hardly realized were there.
For what it's worth, I grew up with a similar background and in the same general location (Chattanooga, TN area). I too did the whole doubting/fear thing while I was a Christian and then later walked away from it (or perhaps it's better to say that it stopped fitting in my head).
It's only natural to still have some of these fears. You are coming out of a monolithic mindset that considered every other viewpoint as wrong, alien, and deluded. Two major elements of control in this mindset are 1) the fear you are being deluded by Satan if you step away from orthodoxy and 2) the fear you will go to hell if you step away from orthodoxy and the church. I'm convinced that if it wasn't for these two components of the religion it would never have spread (or stayed as cohesive as it did) and we'd all still be worshiping Jupiter and Minerva or some such.
I pretty much went from a Christian view-point to a atheistic viewpoint at first. While I wouldn't refer to myself as an atheist now, I think that process of sweeping away all the latent 'spiritual' cob-webs of my upbringing and looking at things from a vastly different perspective (for me it was meme-theory) helped me start over fresh.
What I've found is that the more I've studied and practiced other ways of thinking--ancient mythologies, atheism, meme-theory, Buddhism, new-age, etc--the more many elements of Christianity look like myth and legend too me (whereas they did not in the past). I also find it surprising that after having dismantled that old 'literal' approach to Christianity and come back to it from a different direction, those same myth-like elements of Christianity now have as much, if not more, beauty and meaning to me, even if I don't necessarily believe that they actually happened.
If you'd like to discuss things more in-depth feel free to PM me.
-Ollie