I think the whole concept of functional drunk is crap. So I never got a DUI, divorce or lost a job, my kids still talk to me and I make a good living. But the longer I am sober the more I view the time spent drinking as lost. Time settling for less. Time not pursuing goals or dreams. Time focused on my addiction instead of my family. That may be functioning but its not functioning at my best. I have little doubt if I had continued to drink all the horrors were in my future, and they still could be if I chose to drink again.
As for your beliefs and AA, there are plenty of people there that chose to not follow religion.
Good Luck
LC