Some claims are scientifically scrutable. Other claims are not. Claims about gods typically tend to make the god in question off-limits to scientific scrutiny. Gods are typically defined as invisible, and disinclined to speak to humans directly. This has the unfortunate effect of making god-claims suspiciously similar to the claims of someone less than honest. It is similar to a boy who claims the dog ate his homework, and is unable to produce the guilty dog. And all kinds of reasons are suggested by Christian leaders why God is unable to step out of the shadows to personally introduce himself. Is this modus operandi similar enough to that of a liar to warrant suspicion?
Note that the number of entities that are internally coherent, but inaccessible to the scrutiny of science is infinite. As long as every entity is removed from the domain of scientific scrutiny, you can posit as many entities as required to fabricate a compelling system of spiritual explanations when physical explanations appear inadequate or are emotionally dissatisfying. Nearly every religious system offers a complex configuration of such entities, usually including at least one benevolent powerful being, and at least one polar opposite malevolent being. These polarized extremes can be invoked to explain any positive or negative event unexplained or inadequately explained by physical causes.
The lack of a finite limit to the number of such scientifically inscrutable entities is why theists can never claim that disproving another ideology makes their own more probable (see #38). If the denominator is infinite, the probability remains at 1/∞.
You will also note that ghosts and fairies and perhaps other proposed entities can be defined in different ways, some definitions amenable to scientific examination, and other definitions safely insulated from from scientific assessment. The primary project of modern Christian leaders appears to be the insulating of the concept of the Christian God from scientific scrutiny. What might be the reason for theologies that center on making the Christian God immune from scrutiny?
Sufficient Reasons To Consider Leaving Christianity 