Before I continue with morality, theology and religion, there's one more issue that needs to be hashed out. What, exactly, is the point of thinking about all this? How does it contribute to anyone's life? Why not just get on with the business of living? Be more practical, man! More grounded! It's against statements like these - and the seeming omniscience of science - that philosophers have been scrambling to justify their own existence for a century or two now, and this is my two cents.
It's a pretty common theme to hear that philosophy is the search for truth. Truth with a big, dignified looking "T." I tend to think this just isn't true. Ultimately, “true” statements are not necessary to achieve the self-reflecting world we want most. Philosophy is fundamentally about creation, not exploration. For the most primaeval human purposes, all that matters is that you believe what you believe. And for the sake of the reading impaired, yet another qualification: this does not mean that all statements are equally true.
This, incidentally, is what I consider philosophy to be: sustained reflective thought. The two terms are synonymous. Everyone does it from time to time. Philosophy is not science; science is calculative thought. Reflective thought is abstract, interested and passionate; calculative thought is concrete, disinterested and cold. This being said, the two are not opposites; reflective thought is both chronologically and existentially prior to calculative thought. Every scientific formula is preceded by the (however unarticulated) reflective idea that forming the formula is somehow important. Calculative thought always rests inside a context of reflective thought.
Why say "sustained"? Reflective thought is common in human life, very common; everyone on some level or another engages in some kind of philosophy. Not everyone is interested enough to make it a hobby or a career, however. It's just a matter of quantity. For thought to be philosophical, it has to be a practice.
So, what place does philosophy hold in human life? For one, it gives philosophers something to do. But of course, it shares this in common with every other human occupation. Being a plumber and being a philosopher have the same basic grounding in human life.
Philosophy as creation - e.g. creating previously unseen links between ideas, or creating new ideas, or creating works that influence others - is one of its vital functions. It shares this with art and literature, however.
Philosophy - which is at least partly reflection upon one's self - can open up a dialogue with one's imago. It shares this with psychology, though. Still not a uniquely philosophical activity.
Actually, as a human activity, I don't think philosophy is fundamentally unique. It shares all of its traits with the rest of the humanities.
(On a side note, this is basically why I flippantly choose History over English for my major, and it is why I feel comfortable switching focuses for my MA.)
None of this still doesn't really answer the question; between the apparent non-importance of "Truth" and the epistemological juggernaut of science, why bother with sustained reflective thought?
It's important to remember that philosophy mixes these traits in a way that the other humanities do not. The building blocks of the discipline are the same, but the structure is different. Philosophy is the conscious attempt to create and reveal new ideas about life; it brings together the aims of psychology and art in a powerful and useful way.
To speak practically - and so maybe a little bit calculatively - sustained reflective thought ferrets out new avenues of behavior and interpretation. It helps us cast our lives and environments in different lights. Even deeply conservative philosophies do this, by the way, though perhaps not very effectively.
When one thinks reflectively, one is trying to arrange the facts, conclusions and judgements they have formed in new ways, ways that uncover new ways of seeing the world. It is psychology, it is literature, it is art.
The limits of philosophy should be discussed too. I don’t believe that particular propositions hold any intrinsic motivation power. Changing or forming one’s belief about proposition X does not mean their behavior will change. Human behavior is not guided by propositions: this must be clear. We do not live by our moralities or our philosophies; we wear them like clothes. Our behavior is not subordinate to what we believe; what we believe is subordinate to our behavior.
Behavioral or psychological change does not come with epiphanies; it does not come when we accept certain intellectual propositions. Our behavior and psychology change as part of a circle; our environment changes us, and we seek to change our environment. Accepting propositions is only a piece of the circle; our relationship to our environment must change in ways we do not have full control over before our behavior and psychology change.
The most practical thing that can be said about philosophy is that it helps us ferret out those aspects of our relationship to our environment that we can change. Philosophy helps us consciously change the clothes we wear; our environment interacts with us differently upon that basis, thus bringing about a more holistic change. Philosophy is creation - of both ourselves and the world. Other pursuits - art, religion, etc - also “change our clothes”, but they do so in an unreflective manner.