The word "religion" has many meanings in popular speech. That is especially so if we consider how it is used globally for Western and Far Eastern religions. Only in the three Western religions (Judaism, Christianity, and Islam) and perhaps one religion in the Far East (Sikhism) are questions about truth raised. Only the three Western religions have sacred scriptures, each of which claims logical or factual truth for its creedal doctrines and denies that the other two are as true as it is.
The Old Testament is affirmed as the revealed word of God by religious Christians and also by the religion of Islam; but the New Testament and the Koran are not accepted as revealed truth by the Jews, and the New Testament is not accepted as reveled truth by the religion of Islam.
When considering these three Western religions, all of which claim to be based on God's revelation of Himself, we must face the exclusionary character of logical truth. They cannot all be equally true. The question to be decided is which are more true than the others and which are less true.
Only the three Western religions and one Far Eastern religion (the religion of the Sikhs) are monotheistic. Among the religions of the Far East, some are polytheistic and some are nontheistic. They are cosmological. Some are filled with myths that require interpretation and some, especially Hinduism, claim only poetical truth and so do not exclude other religions.
With regard to the religions of the Far East, it is difficult to draw the line between religion and philosophy. Many of these religions, doctrinally considered, are expressions of purely human wisdom, though in them we find common vestiges of religious worship such as the separation of the sacred from the secular, a priesthood, holy men, and ceremonial practice such as fasting, prayer, sacrifices, and holy days.
The basic distinction to be remembered here is that between natural and supernatural knowledge. Natural knowledge, both sensitive and intellectual, is the knowledge we attain by the unaided exercise of our cognitive faculties. In sharp distinction is supernatural knowledge -- the knowledge we receive by divine revelation.
What Christians declare when they recite the Nicene Creed is what they believe as articles of their religious faith. The presence or absence of supernatural knowledge is the critical point of difference between the revealed religions and purely philosophical wisdom. (See Belief and Cognition.)