Revelation is not a religious flourish. It is a claim about where a piece of knowledge came from.
Modern secular epistemology treats knowledge as something built from the ground up: observation, inference, consensus, with no room left for a source outside that chain. Revelation names the alternative: a knowledge claim whose origin is not human observation or reasoning but disclosure from a divine or transcendent agent.
Philosophers of religion break the concept into two working distinctions. Propositional revelation is the direct communication of determinate truths, through words, texts, or implanted belief. Manifestational revelation is the disclosure of reality itself, an event or presence, from which propositions can be drawn but which is not itself made of sentences. A second axis separates general revelation, disclosure available to anyone through nature or reason, from special revelation, made to a specific people, prophet, or text.
The harder question is whether revelation can serve as a foundation, not just one input weighed against others. Reformed epistemology argues that a belief grounded directly in revelation can be properly basic: warranted without needing to be inferred from prior evidence. The standard objection, from Linda Zagzebski, is that this kind of warrant is inaccessible from the inside. A believer cannot always tell whether a belief is genuinely revelation-grounded or has some other, more mundane source. That tension, between revelation as a self-authenticating anchor and the difficulty of verifying it as one, is the live fault line in the philosophy of religion literature.
Source: Stanford Encyclopedia of Philosophy, “Divine Revelation” (2020, rev. 2024) and “The Epistemology of Religion.”