The assertion "I believe in God" is true or false. It cannot be anything else.
Right but what is God? There’s a myriad of different answers to that and most religions a God is not a being as much an idea or force.
This is where it not being black and white comes into play. Answering that question with True of False means you believe my god is what you believe God to be. That’s likely not the case.
Not a cop out it’s just not black and white. You seem to really be struggling with the fact someone could be in a state between believing in God and not.
You’d be surprised how many Christians will tell you they struggle with believing from time to time. The ones who will admit it at least. Many do and to many God is different from one to the next.