Although he has contributed to other areas of philosophy, his main interests lie in the areas of epistemology and philosophy of religion. His work on epistemic justification has been particularly influential, and he has published extensive discussions of religious language.
In Perceiving God (1991), these two interests come together in a detailed account of the epistemology of religious experience. Alston argues that religious experiences which are taken by their subjects to be direct non-sensory experiences of God are perceptual in their character because they involve a presentation or appearance to the subject of something that the subject identifies as God.
He defends the view that such mystical perception is a source of prima facie justified beliefs about divine manifestations by arguing for the practical rationality of engaging in a belief forming practice that involves reliance on mystical perception. (by Philip L. Quinn in The Oxford Companion to Philosophy , 22.)
Together with other philosophers (Alvin Plantinga, Nicholas Wolterstorff, Robert Adams) Alston was involved in setting up the philosophy journal Faith and philosophy and the Society of Christian Philosophers. Alston is a past president of the American Philosophical Association and was one of the core figures in the late 20th century revival of the philosophy of religion. (via Wikipedia)