In this sweeping simile, the story intertwines religion, humanity, nature, and sin, showing that they are all inseparable from one another:
Verse after verse was sung, and still the chorus of the desert swelled between, like the deepest tone of a mighty organ. And, with the final peal of that dreadful anthem, there came a sound, as if the roaring wind, the rushing streams, the howling beasts, and every other voice of the unconverted wilderness, were mingling and according with the voice of guilty man, in homage to the prince of all.
First, Hawthorne describes how the "chorus of the desert" (the sounds of the wilderness) are happening in tandem with the demonic hymn sung by the devil worshippers. When Hawthorne uses a simile to compare those wilderness sounds to a church organ, he's making it seem like the evil sounds of nature and the sacred sounds of hymn are actually two parts of the same piece of music: the human voices provide the melody, and the evil sounds of nature the accompaniment. This underscores the harmony of humankind and nature, and since nature is associated with evil and sin, this makes humanity seem evil as well.
Then, a sound interrupts the singing. The story doesn't specify what that sound actually is, but Hawthorne uses a simile to describe it: it's as if all the sounds of the wilderness (howling beasts, rushing water, etc.) were joining with the voices of "guilty" people to pay their respects to "the prince of all" (the devil). By equating the singing of sinful people with the evil, chaotic sounds of nature, Hawthorne is once again implying that people are not separate from nature—they're one with nature, which makes them just as evil and frightening as the natural world. And if the "prince of all" is the devil, then the implication is that the devil and sin—not God and virtue—are the natural state of the world.
