If we can see philosophy growing out of mythic thought in Greek history, how does one distinguish philosophy from religion, as the two coexists but are distinguished from each other.
Socrates talks about the gods all the time, and it is not clear why he should not be regarded as a religious figure rather than a secular philosopher.
The easy distinction between religion and philosophy in Western history occurs because of the historical accident that the religion of people like Socrates and Plato later ceased to exist. The old gods of the Greeks, Egyptian, Babylonians, Phoenicians, Romans, Celts, Germans, Slavs, etc. were later replaced by one old religion, Judaism, and two new ones from the same tradition, Christianity and Islam.
It is now possible to say "religion" and mean one of those and to say "philosophy" and simply mean "that Greek stuff" (falsafah in Arabic), where the religious side of Greek thought just need not be taken seriously.
The historical circumstances that allow for distinction does not occur in India or China.
Bhagavad Gita, a religious document for Hinduism, is also a fundamental document of Indian philosophy; Gita appears to have been produced by Indian philosophy, the Sankhya and Yoga Schools, then been transformed into a religious document, and finally used for both religious and philosophical (by Vedânta) purposes later on. This kind of thing makes distinctions between religion and philosophy very difficult in the Indian tradition.
Similar difficulties exist for Chinese and Medieval Western thought. Philosophers are easily classified as Christian, Jewish, or Moslem. If philosophy had nothing to do with religion, presumably it would be superfluous to identify Moses Maimonides (1135-1204) as Jewish or Avicenna (Ibn Sina, 980-1037) as Moslem.
One of the greatest philosophers, St. Thomas Aquinas (1224-1274), addressed the issue by distinguishing "natural theology," (based on reason alone) as opposed to "dogmatic theology," (based on revelation). Jewish and Moslem philosophers made similar distinctions and extended that reason could ultimately justify everything in religion.
Definitions for religion and philosophy involves similar distinctions, where the original context of all thought is mythic.
Since myth does not argue, but philosophy does, religion mixes in philosophic elements but always retains an authoritative link to a mythic context.
Mythic context, tends to exert historical authority. Philosophy cannot conjure up historical particulars out of pure reason, but religion always relates its truth to historical particulars, the actual source of the religion or its received tradition.
Contrary to the text on Evolution of human thought, it must be accepted that mythic thought, and so religion, cannot be replaced by philosophy, or by science.
Religion must answer how any discourse can occur when the notion of God, a being who transcends the realm of human experience and concepts.
Can we say anything meaningful about God?
If we can, is there any truth about God?
The "verificationists" of the first half of the 20th century denied the former, and religious people deny the latter.
Many religious people, though they believe that human language can speak meaningfully about God, deny that anything in theological language is literally true about God.
Rudolf Otto (1869-1937) in his classic, "Idea of the Holy (Das Heilige)" in 1917, It's influence extends from C.G. Jung (1875-1961) to the "Chicago School" of history of religion founded by Mircea Eliade (1907-1986).
Kant, In the Critique of Pure Reason (1781), he reworked the distinction between the immanent (within the world) and the transcendent (outside the world) by distinguishing between phenomena and things-in-themselves.
"Phenomena" are how objects appear in our conscious minds. We do not have access to the world outside of the experiences we enjoy through our own consciousness.
Kant believed that consciousness itself, or the possibility of conscious experience, imposes conditions on the manner in which phenomenal objects appear to us, such as forms of space and time, abstract forms of connections between events and objects such as the concept of substance and the relation between cause and effect.
When applied to religion, may not be all so relevant, depending on how it is argued.