“why the fixation on God if one doesn’t believe in one”.
Are you suggesting that I'm fixated on gods that I don't believe in? My "fixation" is on not accumulating false and unfalsifiable beliefs through critical thought. Gods are just one of the many things this method can be used to consider. It's also useful for evaluating and rejecting the faith-based beliefs people hold outside of religion, although these don't have the penetration and permanence that god beliefs have had. This method also allows me to reject faith-based claims about vaccines and elections, for example.
You have a cancer that spontaneously disappears. You don’t know the mechanism and you view it as simply “spontaneous”. I could view it as a God intervention.
If you think that it might have been a divine intervention, then your thinking is essentially the same as mine - maybe a god was involved if such a thing exists, but I have no reason to think that happened, and maybe it was some naturalistic mechanism involving the immune system perhaps. If you exclude the naturalistic possibility and conclude that it was a god, then you have a faith-based belief. If I conclude that it was not a god, then so do I.
you are using the natural and believing that it applies to spiritual
It does. My spiritual experiences are generated by my brain naturally. If you are referring to spirits, if they exist, they are discernible directly or through their actions. Some ideas correlate with experience, that is, they have real referents. There is something outside of the mind that this idea maps the way an accurate roadmap maps the roads, and this map can be used to arrive at a desired destination. They are facts, or knowledge. They can be used to successfully predict future experience.
Other ideas are fantasies. They correspond to nothing real - nothing outside of minds. They have no external referent and therefore cannot be used to anticipate reality. Spirits probably fall into that category. People that hold those beliefs anyways object to the criteria empiricists use and want their own criteria to be applied as you seem to want. That's fine for you, but not for me. You can use whatever method you like to decide what's real, but you shouldn't expect the empiricist to respect those beliefs the way you do or honor the exemption you grant yourself in defense of them. So when you say, "you are using the natural and believing that it applies to spiritual," my answer is "yes, and so should you."
Refusing even to consider the possibility that other positions are worthy of investigating, clearly is evidence of a closed mind.
Open-mindedness is the willingness to consider evidence and to be convinced by compelling evidence. It characterizes empiricism. The opposite characterizes religious belief. The moderator in the debate between Ken Ham and Bill Nye on whether creationism is a viable scientific pursuit asked, “What would change your minds?” Scientist Bill Nye answered, “Evidence.” Young Earth Creationist Ken Ham answered, “Nothing. I'm a Christian.” Elsewhere, Ham stated, “By definition, no apparent, perceived or claimed evidence in any field, including history and chronology, can be valid if it contradicts the scriptural record." You have one example each of open- and closed-mindedness there.
Here's more closed-mindedness. These people are proud of the fact that they're immune to evidence. They esteem this kind of thinking and consider it virtuous:
“If somewhere in the Bible I were to find a passage that said 2 + 2 = 5, I wouldn't question what I am reading in the Bible. I would believe it, accept it as true, and do my best to work it out and understand it."- Pastor Peter laRuffa
“When science and the Bible differ, science has obviously misinterpreted its data. The only Bible-honoring conclusion is, of course, that Genesis 1-11 is actual historical truth, regardless of any scientific or chronological problems thereby entailed.” – creationist Henry Morris
"The way in which I know Christianity is true is first and foremost on the basis of the witness of the Holy Spirit in my heart. And this gives me a self-authenticating means of knowing Christianity is true wholly apart from the evidence. And therefore, even if in some historically contingent circumstances the evidence that I have available to me should turn against Christianity, I do not think that this controverts the witness of the Holy Spirit. In such a situation, I should regard that as simply a result of the contingent circumstances that I'm in, and that if I were to pursue this with due diligence and with time, I would discover that the evidence, if in fact I could get the correct picture, would support exactly what the witness of the Holy Spirit tells me. So I think that's very important to get the relationship between faith and reason right" - William Lane Craig