It is a real story of real human beings who did something heroic. Like President Reagan said, "Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem." Piper draws the book into a Christian worldview. In the above mentioned book, he says:
The greatest cause in the world is joyfully rescuing people from hell, meeting their earthly needs, making them glad in God, and doing it with a kind, serious pleasure that makes Christ look like the Treasure he is. No war on earth was ever fought for a greater cause or a greater king … But oh, what bold risks and daring sacrifices these lesser causes have inspired! … Oh, that young and old would turn off the television, take a long walk, and dream about feats of courage for a cause ten thousand times more important than American democracy—as precious as that is. If we would dream and if we would pray, would not God answer?
Let us, as Martin Luther would say, “speak the amen firmly,” having faith that God will surely hear and say yes to our prayers.