I've never seen an angel. I have seen pictures of angels in art, but not an actual entity that matches or even approximates the description of angels in art and myth. I know people who claim to have seen and interacted with angels and according to some polls, a reasonably large number of people express belief that angels actually exist. I do not believe that they are telling me the truth. Most charitably, I believe they have deluded themselves into thinking a prosaic experience involved angels. But even if I were to grant that these people were honestly self-deluded, I would still disbelieve the truth of the matter asserted, which is the existence of angels. A tale of a phenomenon attributed to angelic activity would inspire me to mentally search for any possible alternative explanation that was even remotely more plausible than the one proffered.
Indeed, even if it turns out to be the case angels have an objective reality that I have simply missed out on, and you have had a direct, personal experience with an angel that was not a hallucination, chances are pretty good that you won't condemn me very much for not believing in angels and that you would agree that without more evidence than someone else's say-so, I am within the realm of reasonable behavior to disbelieve in angels.
For some people, angels are every bit as real as New Zealand. I've never been to or seen New Zealand; I have no direct, personal knowledge of New Zealand. I know people who claim to have seen and been in New Zealand and even met people who claim to have been born and lived there for a time. But I have no way of knowing if they are telling me the truth about their experiences. It is not difficult to seek out news from New Zealand on the internet, but it's not hard to find things that aren't true on the internet, either. I have seen pictures of what purports to be New Zealand in movies, photographs, and on maps. But I have no way of knowing if those images were not of some other place and simply part of a massive conspiracy on the part of others to convince me that there is such a place as New Zealand. Nevertheless, I have not the slightest doubt that other people are telling me the truth and that New Zealand really, objectively exists.
So -- angels are fiction, New Zealand is reality. I have no personal, direct experience with either. This seems to be a very reasonable way of dealing with the world. What is qualitatively different about my experience of angels as opposed to my experience of New Zealand?
If my use of "angels" as an example offends you because you believe in angels, substitute "fire-breathing dragons" in their place. The point is, it is eminently reasonable to disbelieve in angels and eminently reasonable to believe in New Zealand. Why is that the case instead of the converse or some other combination of those two states of belief?
I have an instinctual grasp of the qualitative difference between a belief in angels and a belief in New Zealand. But I find I have trouble articulating that difference. It's not simply that I trust the New Zealand advocates and mistrust the angelic advocates. It can't be my personal experience; I have no more experience, memory, or other direct sense data about New Zealand than I do about angels. Some of it has to do with references to New Zealand that I can find in source material that I deem to be authoritative, but again, this is obviously insufficient to justify reliance on or prefer one kind of reference (an atlas) as opposed to another (the Bible).
It has to do more with an understanding of the diversity and wealth of different source material supporting the proposition that New Zealand exists as opposed to the source material supporting the proposition that angels exist. I read an atlas, and it tells me that both Florida and New Zealand exist. I have had direct, personal experience with Florida; I've been there, lived there, and have memories of direct sense data accumulated with respect to Florida. This correlates strongly with similar claims made by other people about Florida; their stories seem very similar to my own memories and sensations. Because some of these people and some of these references are congruent with experiences I have had, I give them a presumption of veracity which I do not with those whose experiences are deeply incongruent with reality as I know it to be, like claims about angels.
This strikes me as at best a partial explanation. People I otherwise trust and even rely upon believe in angels and make reference to their existence. Women report to me that childbirth is uncomfortable, often to the point of being painful. I believe these women, but not only do I lack experience with which to verify or correlate their claims, as a male, I can never acquire such experience. I could, in theory, travel to New Zealand and experience it for myself, assuming that it exists. Even if I undergo gender reassignment surgery, the accident of my being born biologically male means that I will never have the experience necessary to directly verify a claim that giving birth is painful. But again, there is something about the quality of the claim that would make it unreasonable for me to disbelieve in the pain of childbirth which is different from a claim that there are fire-breathing dragons alive somewhere on Earth right now.
What I have difficulty articulating right now are philosophically robust qualitative differentiations between claims which are reasonable and those which are unreasonable. Something is not reasonable simply because I say it is, it is not reasonable simply because my instincts tell me it is so. There must be some principled way to differentiate between a reasonable and unreasonable claim; I find that I lack the training or language to accurately describe what I'm getting at.