Perhaps there should be an "undecided" button. Some might say that's a "no", but I'd say, no, that's not a "no, I don't believe in God", it's "I haven't quite made up my mind".
It would cloud the nice little polarity seen with "yes/no", but IMO better reflect the opinions.
I take all these "yes", "no", "undecided" opinions with a grain of salt; the "yes, indeed!" learned on ma & pa's laps and the local church by convention could easily turn into a "no, for I was forsaken when I was in need though I had faith". And the "no, I'm doing quite fine by myself thank you", can easily turn into "God I have need, please help me". And I unbelieve in the "yes", "no", "undecided" being barriers among ourselves, though I have no wish to join in most "yes" or "no" congregations, nor "undecided" for that matter, and recognize that self-imposed barriers will exist.