For many mystics, god is not an idea but an experience. Precisely speaking, the god of the mystics is the experience that one seems almost certain to have should a person’s subject/object perceptions abruptly end, thus dissolving the process that creates the self, while experiencing yet continues.
That god, the god of some mystics, is incomprehensible. It can be experienced, but it cannot be believed in. “…God is not a conviction: it is an experience not based on any belief or dogma, or on any previous experience. If you have an experience born of belief, your experience is the conditioned response of that belief.” Any belief one has about that god no matter how subtle; or any knowledge one has of that god by a previous experience no matter how true; will work to prevent one from experiencing that god, the god of the mystics, which, so far as I know, is the only god that can be experienced.
Even the very word, “god”, is a ridiculous and most likely foolish attempt to describe the experience that occurs when subject/object perception ends while awareness yet continues. Why call that experience, “god”, unless you mean to in some sense describe the experience? And doesn’t calling the experience, “god” — doesn’t describing the experience that way — become an expectation, an idea, that works to prevent the experience from occurring?
It’s tradition for a few mystics to call a certain kind of experience, “god”. I guess that has some limited utility, which I won’t get into here, but it’s almost certain to work against the experience itself. At least, that’s how I see it.