Part of the problem comes from the particular ways in which philosophy and religion have come be understood in the modern West.
Philosophy is split up into different schools of thought. Some schools restrict themselves completely to the study of logic and the meaning of words (“logical positivism”) and believe that all other forms of philosophy are at best “poetry” and at worst misunderstanding (“category mistakes”.) Others see philosophy as being the study of ideas in society and spend a great deal of time trying to figure out the cultural context of our fundamental notions (“deconstruction”.) Others believe that philosophy is about trying to find some sort of personal accommodation with the inherent absurdity of existence (“existentialism”.) The list goes on and on. But what all of these different schools currently have in common is the fact that they have become professionalized in the university setting. In effect, the only people who “do” philosophy anymore, are professors and students. And the only place it gets “done” is in university classrooms and academic journals.
This contrasts with another, more popular and ancient way of understanding “philosophy”.
The iconic image of philosophy for most of history has been that of people like Diogenes wandering with a lamp in broad daylight looking for an honest man. Or Socrates asking questions of young men in the market of Athens. At those times and places, being a “philosopher” wasn't a job, but rather a vocation or calling. And it was often one that dramatically changed your lifestyle and involved adopting a specific, visible role in society. For example, at the time of the Roman empire the convention was that only men who identified themselves as “philosophers” wore beards. (If you look at Roman coins, the only emperor wearing a beard was Marcus Aurelius---who was also a stoic philosopher and wrote the famous Meditations.)
Beyond such outward signs of eccentricity, philosophers were traditionally known as being people who often had a very well-developed mystical streak. Socrates had his “daemon”, or mysterious voice that would tell him whenever he was about to do something wrong. Descartes, Thomas Aquinas, Plotinus, Plato, etc, all described experiences that they had had which were very similar to those of religious mystics.
Even those philosophers who espouse belief systems that would not seem to have much in common with religion or mysticism often use gnomic language that could easily fit into a religious context. Take a look at this famous quote from Ludwig Wittgenstein:
"My propositions are elucidatory in this way: he who understands me finally recognizes them as senseless, when he has climbed out through them, on them, over them. (He must so to speak throw away the ladder, after he has climbed up on it.)"
Isn't this exactly the sort of statement that one would expect from a Daoist, Sufi or Zen Master?
In addition to these superficial similarities between philosophy and religion, there has traditionally been a specific thing known as being "philosophical". For example, you will sometimes hear common folks say things like “He took the news about losing the money philosophically.” In this situation, the term has nothing at all to do with a specific school of academic thought, but rather a habitual way of engaging with and responding to the world around us. One dictionary defines this as being "rationally or sensibly calm, patient, or composed". This isn't exactly the same thing as being “holy” or “saintly”, but it does seem to have some overlap with that way of describing a person.
These superficial similarities between religion and philosophy need not be mysterious in nature, once one realizes that philosophical investigation has a great deal in common with the spiritual practices of many religious traditions. This involves a lot of time spent in quiet reflection, careful analysis of traditional texts, pondering one's assumptions about life, and, deep reflection on what it means to be a human being. In most religious traditions, this activity would all be labeled “prayer”, “meditation” or “contemplation”. The point is that the practice of looking at the world logically is not only an academic discipline, but it can also be very akin to a spiritual practice, one that can have a practical impact on a person's personality.
Just as people often talk about the solace that people gain from religion, so too there is a sense of peace that comes from philosophy. Indeed, one of the most popular works of literature in the middle ages was Boethius' Consolation of Philosophy, which was written while the author was in prison waiting to be beaten to death with cudgels for the crime of treason against the Roman Emperor. Another example are the Stoic philosophers who taught that the good life is in the grasp of most people, but must be worked for through the use of reason and self-discipline. Ancients like Epictetus would even sometimes write “self-help” manuals that would contain such pithy advice as "Regardless of what is going on around you, make the best of what is in your power, and take the rest as it occurs." (Think of this as the philosophical equivalent of St. Francis' “Prayer of Serenity” that is hung on the walls of countless Christian households.)
At the same time that the West was driving philosophers out of the marketplace and locking them up in the Ivory Tower, it was also chasing religious people out of the hall of reason. That is to say, a certain way of understanding religion that is antithetical to philosophy has gained public prominence to the point where many folks believe that it is the only way to understand the term, and as such, believe that there is no common ground between “faith” and calm, reasoned reflection. Primarily, this understanding of religion comes from a 20th century reactionary movement against liberal values and the modern world known as “fundamentalism”. (This movement began as a form of North American Christianity, but the same tendency has asserted itself in all the world's religions.) In a nutshell, fundamentalist Christianity is based on the assumption that all “true” Christians believe the following: the literal and total inerrancy of the Bible, the virgin birth of Christ, the doctrine of substitutionary atonement, the bodily resurrection of Jesus, and the authenticity of his miracles. (Forms of fundamentalism based on other religions would obviously come up with a different set of “fundamentals”.)
For followers of this doctrine, the cornerstone of religion is not how one lives one's life, treats one's neighbours, or grows as a human being, but whether or not one publicly associates oneself with and actually believes these assertions. Please note what an enormous demand this is to make of someone. Our democratic system of government is based on the principles of freedom of speech, association, the press, etc. Parliaments and Congresses are based on the ability of elected representatives to ask the government searching questions in order to find the truth. As citizens we depend on the media to investigate and chase down news that is of public interest. In addition, the material prosperity we enjoy is based on the cultural practice of scientific investigation. Fundamentalism wants the citizenry to turn this deeply rooted intellectual freedom totally on its head and instead simply accept whatever the church teaches them to believe without any hesitation or doubt whatsoever.
Please take another moment to consider how great this demand is. Even Caligula understood how difficult it is to control a person's inner being. That is why he coined the famous dictum: oderint, dum metuant (“Let them hate, so long as they fear”.) The theology of the fundamentalists is even more oppressive than that of the mad Emperor---it is not satisfied with just fear and lip-service but demands total, robotic unity of thought.
As such, the followers of fundamentalism are forced to simply turn off their curiosity and faculty of reason or else accept that they can no longer be members of the religious community. In this formulation, therefore, “faith” is defined as the ability to cease to act like a rational human being who has been socialized to live in a democratic, science-based community.
The important point to realize about this sort of belief system is that it is based on fear. On the surface level, the concern is that if someone isn't able to keep the rational mind at bay a vengeful God (or at least an angry congregation) will cast her into a “fiery pit”. On a deeper level, the fear is that once a person looks at religion using the same thought processes that allow him to wire his home without electrocuting himself, he is inevitably going to find out that it is nothing more than a sham. This puts the fundamentalist believer in the same situation as the man who has a re-occurring cough that he constantly worries about, but who refuses to go see a doctor about for fear that it may turn out that he has lung cancer.
A second thing to remember about the fundamentalist world-view is that it is primarily concerned about the internal thought processes of the practitioner rather than her behaviour. It doesn't matter whether or not this person lives a saintly life, if she doesn't believe, she is doomed by a vengeful God. Indeed, the most wretched sinner who believes or even recants on his deathbed is assured a place in heaven while the secular or even liberal religious saint who cannot find it in herself to believe in the fundamentalist creed is doomed to the fiery flames of Hell. Not only does this offend against people's innate sense of justice, but because a person's behaviour is intimately connected to their psychological state, it would appear that, for the fundamentalist, religion has no impact on a believer's psyche than the simple “leap of faith”.
Not only does this reduction of all religious behaviour to belief dismiss good works as irrelevant, it also rejects the value of any sort of spiritual practice. This means that not only does the fundamentalist believer not have recourse to their rational mind, they are also totally cut off from any sort of personal interaction with the spiritual plane. No insight gained from personal insight or spiritual self-transformation is allowed to trump the viewpoint of the fundamentalist, because the ultimate authority is the literal word of the Bible (as interpreted by the fundamentalist preacher, of course.) In effect, no matter how many years of spiritual practice an individual man or woman has followed, or how wise they appear in both word and deed, they have no authority at all compared to an ancient anonymous scribe writing in bad Greek.
My experience with Westerners who identify with “philosophical Daoism” (daojia) and fight tooth and nail against the idea that Daoism is primarily a religion (daojiao) is that they usually consist of folks who make the assumption that by definition all religion is fundamentalist in nature. Conversely, once in a while, I will come across someone who is upset about Western cultural appropriation of the Daoist “brand-name” and will violently argue that nothing in the religion (as they espouse it) should ever be questioned. As a result, they assert that “philosophical Daoism” as such simply does not and never should, exist. As such, they come very close to espousing a form of “fundamentalist Daoism”, which immediately drives the first group totally ballistic. Since these latter folks only reinforce the assumptions of the former, the result is extreme reluctance for Westerners to entertain the notion that there is anything at all worthwhile in the traditions of any religion, let alone Daoism.
This is unfortunate, for while it is true that the fundamentalist definition of religion life is quite common and has been very forcefully promoted by various institutional forces in modern society, it is not currently, nor has it ever has been, the only one. A different formulation of “faith”, for example, is to see it more as a form of “hope” in the ultimate meaning of life instead of robotic assimilation by some simplistic creed. The distinction is that the fundamentalist is terrified that if he follows his logical faculty wherever it leads him, it will undermine his religion and leave him in a place that he does not want to be. The person who's faith is based on hope, on the other hand, trusts that wherever reason leads her it will eventually take her to a place where she will be comfortable. In effect, a great deal of the distinction comes down to whether or not one lives in spiritual fear or courage.
The Westerner who rejects the religious side of Daoism is not just rejecting fundamentalism, however, he is also cutting off some of the most fruitful parts of the tradition he espouses. Logic is not only deductive, it can also be inductive. That is to say, reason is not only restricted to analyzing statements to find out if they conform to the standard rules of set theory and truth-functional analysis; but it also includes the pursuit of direct experience in a systematic and rational way (i.e. the scientific method.) Reason allows for experimentation as well as logical analysis. And this is where the religious side of Daoism has things to offer that simply reading the Dao De Jing, Zhuangzi and a few other texts cannot.
The Daoist tradition includes a wide variety of martial arts and meditation techniques that are all seen as specific methodologies that allow an individual to directly experience that ineffable entity that writers like Laozi, Zhuangzi and Liezi call the “Dao”. These techniques are also integral to the spiritual project of becoming a better human being (“internal alchemy”.) If someone rejects all of the religious elements of Daoism, they reject this rich heritage too.
Finally, people are much more than thinking machines, we also feel, are inspired, love, appreciate beauty, and so on. The rituals, aesthetics, calligraphy, fengshui, etc, of Daoist tradition all respond to these other elements of what it means to be a human being. The exercise of reason is not opposed to any of these things, and it could become an enormous asset to them by helping the practitioner make distinctions between what should be accepted as a useful ornament to human existence, and what should be rejected as superstition. Simply restricting yourself to reading the Dao De Jing, Zhuangzi and a perhaps a few other texts cuts these people off from this entire artistic universe. This is unnecessary and wasteful.