It is not really "sensible". The reason is because we are responding to the claims of existence made by theists. What kind of evidence would you expect "nonexistence" to leave? By definition, nonexistence cannot leave any evidence because it is "nonexistent". So if things that really exist are the only things that can leave "evidence" that they are indeed there and theists are claiming that magical super Beings are indeed there, it is their sole burden to share the evidence that should be readily available that they used to know for themselves that Gods actually exist or even "possibly" exist. As much as I would love to believe in a real magical Santa Clause, I have "no choice" but to lack belief in such a magical Santa because there is no supporting evidence and no supporting reasoning that would allow me to either know the magical Santa exists or suspect that existence might be possible. A good example of proper agnosticism over a concept is life on this planet granting the "possibility" of other life to be agnostic about. To be agnostic of Gods is as reasonable as being agnostic of all magical beings/creatures who share the same demonstrated "possibility", which is zero. Who wouldn't want a magical super Being who loves us and will grant us a blissful, eternal life? So it really isn't because I "choose" not to believe, theists simply have painted a case for their Gods that appear to be born out of superstition and ignorance of nature. If a theist could ever make a "reasonable" case for Gods, I would certainly move to an agnostic position, but I need that "possibility" reasonably demonstrated otherwise my agnosticism would be irrational where the only current reason to be agnostic is where the "possibility" is granted purely on the number of superstitious people claim they are real.