"I never found his work believable,"

So is the refrain of many lovers of fiction who find that their ability to suspend their disbelief snaps at a point at which millions of others are able to sustain it.

I read fiction on the belief that it's ALL make believe nonsense, just some make-believe nonsense is more internally consistent - and thus 'believable' - than others. I include well composed fiction of the fantasy genre in that camp.