But as it is presently defined and taught in the West, philosophy is the answers to all these questions without God, or without 'revelation' from God.
So the philosopher sits down without a Bible (or any 'holy book' for that matter) and ponders a subject: war, marriage, and so on, using whatever tools are around her (history, culture, writers, human reason).
Here are five immediate limitations she comes up against:
One tool she will use is Experience: she will draw on her own past and present experience. Trouble is that being finite and located in only one family, one culture, one nation and one short span in history, her experience will be miniscule. Any philosophy based upon it will inevitably be open to revision and change in the light of a broader experience.
Another source of philosophical wisdom would be the way we find things around us in the world. If you were born into a culture that glorified violence (the Roman world, for example) or tolerated slavery or tolerated abortion, you could easily grow up assuming these "ares" were "rights" (plenty of mothers, yes mothers, fought against the eradication of chimney sweeps, a cruel occupation for a child if ever there was one. Why, because that's just the way things "were" growing up in that age).
Suppose we go to the experts to inform our philosophy. They could also so easily be wrong. Few experiences are more amusing than reading an ancient philosopher describe the natural world! New textbooks are written every year to correct old information. What the experts say in one decade is overturned in the next. Sometimes, as in the case of Marx and Mao, not before considerable carnage has been done to and by the followers of false systems.
Suppose there are keys or key pieces of information that simply cannot be known without 'revelation'? Suppose there are secrets which only the Creator can reveal to us, information which simply can't be found by us, no matter how big the research programme? Any philosophy which did not take them into account would then prove faulty.
For all these reasons philosophy has severe limitations.
The overarching reason all human-without-God philosophy is flawed is this: the people who create it are tiny and finite and in the Great Scheme of Things, they simply don't know that much at all: none of us do, that's why we need Revelation.
Philosophy is like a bridge that gets us a tiny distance to the land of truth. But we need revelation to get to the other side - not attached to the partial bridge of philosophy, but making the whole span.