Disclosure by God of himself and his will to the human race. The disclosure comes to human beings by way of communication, which implies the communicator, who is God; the receiver, who is the human being; and a transmitter or intermediary. Depending on the intermediary, there are in general two main forms of revelation, commonly called natural and supernatural.
If the intermediary is the world of space and time, the revelation is said to be natural. In this case, the natural world of creation is the medium through which God communicates himself to humankind. Moreover, humanity's natural use of reason is the means by which it attains the knowledge that God wishes to communicate. It is therefore natural twice over, once in the objective source from which human beings derive knowledge of God and divine things, and once again in the subjective powers that a person uses to appropriate what God is revealing in the universe into which humanity has been place. In the Old Testament those are said to be "naturally stupid" who have "not known God and who, from the things that are seen, have not been able to discover Him-who-is or, by studying the works, have failed to recognized the Artificer" (Wisdom 13:1). And St. Paul affirmed: "Ever since God created the world his everlasting power and deity--however invisible--have been there for the mind to see in the things he has made" (Romans 1:20).
Supernatural revelation begins where natural revelation ends. It is in the character of grace from God who has decided to communicate himself in a manner that far exceeds his manifestation through nature. The Scriptures call this form of communication a divine speech and refer to God as speaking to humankind. There are two levels of this supernatural revelation, as capsulized by the author of Hebrews: "At various times in the past and in various ways, God spoke to our ancestors through the prophets; but in our own time, the last days, he has spoken to us through his Son, the son that he has appointed to inherit everything and through whom he made everything there is. He is the radiant light of God's glory and the perfect copy of his nature (Hebrews 1:1-2).
The difference between these two kinds of supernatural communication lies in the fact that, before Christ, God spoke indeed but still indirectly through the prophets who were inspired to tell others what Yahweh had told them. In the person of Christ, however, it was no longer God speaking merely through human seers chosen by him; it was God himself speaking as man to his fellow members of the human race. (Etym. Latin revelatio, an uncovering; revelation.)