I agree with the mission of the thread, even if I disagree with some of the arguments given for.
A: The reason why someone has or lacks belief is a different topic, with atheists often replying they don't see strong enough evidence and theists using personal experience — both of those are valid even if perhaps insufficient.
B: When we ask whether someone believes something, it is a yes or no question. When we ask someone "do you believe there is life in another planet", the answer is either yes or no, as the person weights the evidence in their head. The correct answer would be "I don't positively believe either way, but given the following facts, I believe it is more likely that...", but humans don't talk like that, we say "I (/do not) believe in it".
C: Are you sure that you will wake up tomorrow? No, I could have a stroke in my sleep. Do I have any reason to believe that will happen? No, so I believe I will wake up tomorrow.
The same applies to the Sun rising. Maybe the Sun is massive enough to form a supernova, maybe a supernova can happen from one day to another, maybe an asteroid will hit the Earth and shatter it, or maybe stop its spin, maybe the United Nations did not tell us anything about any of those for some reason! It is possible. Do I believe any of those are the case? I don't believe them, because if I believe that today, I should have believed it all the other past days, because the evidence is the same (none), and it did not happen in any of those days, so I am safer saying it won't happen tomorrow either.
D: It is hardly the case that someone is truly neutral on a topic, even if they purport to be. Given a topic with more than one argument for it and against it each, each argument can have sway in a person that goes from 0 to 1, and there are infinitely many possibilities between 1 and 0 — not convinced at all by that argument being 0 and 1 being fully convinced. Being that most topics have several arguments surrounding it, it is extremely unlikely that the evidence's sway in someone's head falls exactly in the middle between belief and disbelief.
From B and D, when we ask someone whether they believe in God they should say yes or no, the uncertainty of the topic is already implied, stating whether you are an agnostic theist/atheit is redundant, and any gnostic theist/atheist has an almost impossible-to-meet burden of proof, so I say the gnostics here are either lying or confused. The agnostic label should be reserved for those who are truly divided (even if the evidence sways their mind in another direction) and prefer to suspend judgement in the await for more evidence.