The fact that there is a plurality of religions is significant in different ways from different points of view. From a skeptical point of view their different and often incompatible beliefs confirm the understanding of religion as delusion. Thus, Bertrand Russell wrote that "It is evident as a matter of logic that, since [the great religions of the world] disagree, not more than one of them can be true" (1957, xi). From the point of view of an exclusive and unqualified commitment to any one religion the fact of religious plurality is readily coped with by holding that all religions other than one's own are false, or false insofar as their belief systems differ from one's own. But from a point of view that sees religion as a worldwide phenomenon that is not to be dismissed in toto as delusion but as the human response to a divine/transcendent/ultimate reality, the fact of plurality poses a major philosophical problem. On the one hand, the "great world religions" seem—to many impartial observers, at any rate—to affect human life for both good and ill to more or less the same extent. But on the other hand their respective belief systems, although having important similarities, also include starkly incompatible elements. According to some the Real (a term at home in the Judeo-Christian tradition and corresponding to the Sanskrit sat and the Arabic al-Haqq ) is personal but according to others not personal. And within each group of religions there are wide differences. Is the ultimate Person the Christian Trinity or the Qurʾanic Allah, or the Adonai of Judaism, or Vishnu, or Shiva? Is the nonpersonal Ultimate the Brahman of advaitic Hinduism, or the Dao, or the Dharmakaya or Void or Nirvāṇa of the Buddhist traditions? And how could the Real be all of these at once? The logic of religious difference here is in fact very complex, as is shown by William Christian's analysis (1987).
The problem is particularly acute for a major form of religious apologetic that became prominent in the 1980s and 1990s. This holds that the basic empiricist principle that it is rational, in the absence of specific overriding considerations, to base beliefs on experience should be applied impartially to all forms of putatively cognitive experience, including religious experience—unless, again, there are specific overriding considerations to the contrary. This has been argued directly by William Alston (1991) and others and indirectly by Alvin Plantinga (in Plantinga and Wolterstorff 1983), whose defense of the rationality of holding "properly basic" religious beliefs presupposes religious experience as their ground.
Most of the philosophers who employ this kind of apologetic have applied it only to specifically Christian beliefs. But it is evident that precisely the same argument is available for the belief systems of other religions. If Christian religious experience renders it epistemically justifiable (subject to the possibility of specific reasons to the contrary) to hold Christian beliefs, then Buddhist religious experience renders it epistemically justifiable, with the same qualification, to hold Buddhist beliefs, Muslim religious experience to hold Muslim beliefs, and so on. Thus, anyone who maintains that the Christian belief system is true, but that the belief systems of Buddhists, Muslims, and so on are false insofar as they differ from it, has implicitly reversed the original apologetic and is presenting Christian religious experience as the sole exception to the general rule that religious experience gives rise to false beliefs!
Alston, recognizing the challenge posed by the fact of religious diversity to the experiential apologetic, has responded by saying that in this situation it is proper for the Christian to continue within her own belief system, despite the existence of other equally well-justified alternatives, while, however, she seeks "a way to show in a non-circular way which of the contenders is correct" (1991, p. 278).
An alternative use of the experiential apologetic rejects the assumption that only one of the different religious belief systems can be true. This approach (Hick 1989) distinguishes between, on the one hand, the ultimate religious reality, the Real, beyond the scope of our (other than purely formal) human conceptualities, and, on the other hand, the range of ways in which that reality is humanly conceived, and therefore humanly experienced, and therefore humanly responded to within the different religiocultural ways of being human. The epistemology operating here is one that, in the Kantian tradition, recognizes an important contribution by the perceiver to the form a reality is perceived to have. As Thomas Aquinas wrote, "Things known are in the knower according to the mode of the knower" (Summa Theologiae, II/II, 1, 2). And in religious knowing the mode of the knower differs from religion to religion. From this point of view the fact of religious diversity does not constitute a challenge to the experiential apologetic but rather a series of examples of its valid application.
Other philosophical responses to the fact of religious plurality, not specifically related to the experiential apologetic, include the "perennial philosophy" (e.g. Schuon 1975, Smith 1976), which distinguishes between the essence (or esoteric core) of religion and its accidental (or exoteric) historical forms. In their esoteric essence all the great traditions converge in a transcendental unity, the Absolute Unity that is called God. Experientially, this sees the mystics of the different religions as participating in an identical experience, although they articulate it in the different ways provided by their traditions. This view is opposed by those (e.g., Katz 1978) who hold that all experience is concept laden and that mystical experience accordingly takes different forms within the different traditions.
There is also the view of John Cobb (in Kellenberger 1993) that the religions are directed toward different ultimates, particularly the personal reality worshiped in the theistic religions and the nonpersonal process of the universe experienced in Buddhism. Yet other constructive suggestions include those of Joseph Runzo (1986), James Kellenberger (1989), and the authors included in the symposium Inter-Religious Models and Criteria (Kellenberger 1993).
Alston, W. P. Perceiving God. Ithaca, NY: Cornell University Press, 1991.
Basinger, David. Religious Diversity: A Philosophical Assessment. Burlington: Ashgate, 2002.
Godlove, T. F. Religion, Interpretation, and Diversity of Belief. Cambridge: Cambridge University Press, 1989.
Griffiths, Paul. Problems of Religious Diversity. Oxford: Blackwell, 2001.
Katz, S. T., ed. Mysticism and Philosophical Analysis. London: Sheldon Press, 1978.
Kellenberger, J. God: Relationships with and without God. New York: St. Martin's Press, 1989.
Kellenberger, J., ed. Inter-Religious Models and Criteria. New York: St. Martin's Press, 1993.
Krieger, D. J. The New Universalism. Maryknoll, NY: Orbis, 1991.
McKim, Robert. Religious Ambiguity and Religious Diversity. Oxford: Oxford University Press, 2001.
Plantinga, A., and N. Wolterstorff, eds. Faith and Rationality. Notre Dame, IN: University of Notre Dame Press, 1983.
Quinn, Philip, and Kevin Meeker, eds. The Philosophical Challenge of Religious Diversity. New York: Oxford University Press, 2000.
Runzo, J. Reason, Relativism, and God. New York: St. Martin's Press, 1986.
Russell, B. Why I Am Not a Christian. London: Allen and Unwin, 1957.
Schuon, F. The Transcendent Unity of Religions, rev. ed. New York: Harper and Row, 1975.
Smith, H. Forgotten Truth. New York: Harper and Row, 1976.
Vroom, H. M. Religions and the Truth. Amsterdam: Rodopi, 1988.
John Hick (1996)
Bibliography updated by Christian B. Miller (2005)