This is my experience...i "believed" in God when i walked into AA, a judgemental, punishing, vindictive God who hated me as much as i hated myself and i thought i was definitely going to Hell, i was taught about this God in school, at Church i was forced to go to at school and it was re-enforced by media and some people...
I then found out that this isn't true at all and God is a word that is used to describe whatever a person believes in as a higher power, anything ranging from what i believe which is an entity that is just plain loving and is the creator of everything (not a man with a beard) to, what i also believe too, the energy that we are all made up of, this has been proven by sceience, which can neither be created or destroyed...basically we aren't just a body! Some people in AA look to gravity as their higher power, assuming that you can't levitate yourself to the clouds, and other use the group of people in the room as their higher power, i.e. the love and compassion that comes from alcoholics helping other alcoholics...it's so open!
Fundamentally as long as you believe that there is a power greater than you, remember i mentioned gravity, and it is NOT you...i.e. you aren't running the world or in control of everything, which is insane insane thinking in itself because our bodies will all die...i guess anyone who is going to live forever would have a problem with this concept?!
There is a huge stigma about this God thing created by people outside of AA who base their opinions on the teachings of religions, which i did too, so get down there and prepare to be pleasantly surprised!
There is a whole chapter in the Big Book "Chapter to the Agnostic" which will help too...agnostic meaning that the person accepts that whether there is a God or not cannot be proven and is therefore as mute a point as whether the easter bunny exists...athiests, on the other hand, absolutely do not believe in God and, in my experience, will fight their corner to prove that God does not exist which i've always found weird cos i don't believe in the easter bunny but you don't see me citing sources and getting upset if someone else does...i've always found the athiest as fanatical about their belief, or as they would say non-beliefs, as the religious sort...weird huh?!
Anyways a good convo to be had over coffees with the many people you will get to know! Like you said stay open-minded and on midddle ground with this one and you will be fine:-)