....Of course people can not believe in things. Do you believe in the existence of thing X whose existence cannot be proven or refuted? I highly doubt that you do.
Further, you can have reasons for not believing in something, and still sensibly call that unbelief. If I don't believe in unprovable-irrefutable thing X, my reasons for unbelief can be because I reject that any such thing can exists, or perhaps that even if such a thing can exist I have no good reason to accept that it does in fact exist.
Further, you can have reasons for not believing in something, and still sensibly call that unbelief. If I don't believe in unprovable-irrefutable thing X, my reasons for unbelief can be because I reject that any such thing can exists, or perhaps that even if such a thing can exist I have no good reason to accept that it does in fact exist.