A few minutes looking at derivations will show you that the meaning of “reason” has somewhat mutated over time.
The word goes back to the Latin “ratio” (where we get rational), which means think or judge. Apparently “think” is equivalent to “thank”, which obviously means to favour - as a judge does when discerning the verdict.
“Discerning”, like similar words such as “discriminating” or showing “discretion” derive as “separating”.
“Thinking”, “judging” or showing “reason” goes further by siding with one side of a separation rather than the other.
Being reasonable by way of making “sense” or being “sensible” - nowadays synonymous with being understandable and logically valid, comes from the Latin for sensation: deriving just as much from feeling as understanding. “Logic” derives very similarly to reason, except from the Greek rather than the Latin. The word “intelligent” derives very similarly to “reasonable” too - as the ability to choose between. An intelligible person is understandable by virtue of their clarity in distinguishing one thing from another through speech. “Logic” and “reason” are both associated with speech by derivation. (I have heard it suggested that reason was born and is inherited from mankind’s traditional success through distinct, clear communication).
All of this seems to indicate an original lack of separation between thinking and feeling. Being reasonable would be associated with going one way rather than the other regardless of how you made that decision, either through giving it a great deal of thought or simply acting on a whim.
It would also indicate that intuitive faith from denoting a simple “feeling” as the existence of deities was just as reasonable as deducing anything’s existence through a protracted methodology.
(There is an irony here that not separating intuitive faith from methodological proof, and favouring one or the other, is unreasonable - when reason is equivalent to separation and favouring…
And if reason is distinguishing between things and favouring between one or the other, then to distinguish between “distinguishing” and “undoing distinctions” and to favour the latter would also be reasonable…)
Yet now, there is very much a separation between thinking and feeling, and only the former has inherited its Latin roots.
Humanity has traditionally celebrated and given thanks to its ability to control its underlying animal nature - this is a great deal of what has been attributed to mankind’s success, dominance and superiority. This thanking, or thinking, is given to protracted methodology rather than instinctual gut feeling. This has been understood as a distancing of thought from instinctual feeling. In fact, the closeness that derivation suggests between thought and feeling is revealed when one questions the motivations for turning towards thought rather than feeling: since this motivation is based in sentiment.
When one considers something in what we now call a “rational” way, one steps back: nullifies the former emotional connection with the situation and replaces it with an emotional interaction of a different kind, where one dominates mental images of the situation by grasping them as concepts and sorting them to come up with an attempted prediction - the end result being that fear is lessened. Before “reason” as it is known now, this was done by memorising exceptions to rules: specific incidents, and sometimes forming patterns of similarity - but since “reason” became an “artform”, people have been starting from a point of unquestioned acceptance of these exceptions and rules. This is a quick and effective way of getting a decent grasp of “reality” (which derives from “things”), which can then go on to be personalised if this is seen fit to do so.
Those who start from here and have nothing or little in their life to call for such personalisation to their own experience will accept things like deities easily. It is an abundance of the dissociation from instinctual feeling that I mentioned earlier that brings people away from the traditional set of beliefs that have traditionally outlined a rough general sketch of reality. It is an abundance of whatever feeling is involved in “turning away from feeling” to thought. Each is feeling and each is “reasonable”.
“Turning away from feeling” to thought, in accordance with humanity’s traditional celebration and thanksgiving to its success, dominance and superiority, is a kind of self discipline. One learns to deny themselves their basic instincts that make one like an animal in a kind of self-cruelty and self-imposed binding restriction. The word “religion” comes from “binding”. By derivation it would be accurate to compare the discipline of protracted methodological thought to religious practice - whether or not one turns to belief in deities as a result.
Human success, dominance and superiority is also traditionally attributed to the social instinct. It is not surprising that when one stays true to “feeling”, or religiously binds oneself to “thought” that they are personified. The turn away from such personification is a deviation from the social aspect of humanity towards another reason for human success, dominance and superiority - the ability to use things to one’s advantage. The result of thought or feeling being a belief in deities or not is not a question of good reason as each approach is equally reasonable - it is a matter of taste. It is a matter of mankind’s continued dominance being rooted in clear communicable discretion and decision (reason) and in the social and/or creative instincts.