Do we really know what's going on when we pray? When we bow our heads at the dinner table? When we whisper quietly during our morning commute? Or when, like dragging our feet along a well-worn path, we ask again for God to do what he hasn't yet? Do we know what's happening?

The Bible tells us in Revelation 8:1–5.

Here's the picture: The seventh seal — the last page in the scroll of history — has been opened. And there is silence. Seven angels stand before God and each are given seven trumpets. Then another angel approaches the altar carrying a bowl (or censor). This angel is given incense to offer before the throne, with the prayers of the saints. Imagine, then, on this altar are piles of prayers. Centuries of prayers. Your prayers and mine. They are as fire, burning, their smoke rising up from the altar before God. Then the angel takes his bowl to this blazing altar and he rakes in all these flames. Then, holding this bowl of fire — of our prayers — he steps over and hurls it onto the earth.

John Piper concludes,

What God wants us to believe about our God-exalting prayers is that none of them are lost. None are wasted or pointless. They are stored up on the altar of God until the proper time when God pours them out on the earth to accomplish his great purposes of judgment and redemption. (The Prayers of the Saints and the End of the World, January 9, 1994)

Until this point in the Book of Revelation, Piper explains, the apostle John has shown us the awesome sovereignty of God that controls history. But now he shows us something different: our role in it all. That is, we have prayed and the Lord has heard us.

The utterly astonishing thing about this text is that it portrays the prayers of the saints as the instrument God uses to usher in the end of the world with great divine judgments. It pictures the prayers of the saints accumulating on the altar before the throne of God until the appointed time when they are taken up like fire from the altar and thrown upon the earth to bring about the consummation of God's kingdom.

In other words, what we have in this text is an explanation of what has happened to the millions upon millions of prayers over the last 2,000 years as the saints have cried out again and again, "Thy kingdom come . . . Thy kingdom come!" Not one of these prayers, prayed in faith, has been ignored. Not one is lost or forgotten. Not one has been ineffectual or pointless. They have all been gathering on the altar before the throne of God. . . . Not one God-exalting prayer has ever been in vain.

Pray it again, then, that which you've asked. Seek it more, then, that for which you've longed. Expect that God hears, then, because no believing prayer is in vain. Ever.

For another sermon from John Piper on the cosmic magnitude of our prayers, see "Prayer and the Victory of God" (January 1, 2006).