A dark, unidentifiable roar opens Arcade Fire’s brilliant second album and rumbles ominously through the opening track like a thundercloud on the horizon. Moving to the foreground at the end of the song, the noise finally reveals itself: an apocalyptic explosion, destroying everything. “Mirror, mirror on the wall,” murmurs Win Butler, as if watching the end of the world in a trance, “show me where them bombs will fall.”

Three years after Funeral, the exuberant, defiant hooray for life and violins that catapulted this proudly arty young Montreal septet into the saintly kind of fame that leads to David Bowie duets, all is not well with Arcade Fire. Like a bedside diary filled with bad dreams, Neon Bible is a catalogue of strange fears: soldiers groaning in agony, men coming for you in the middle of the night, bad TV and soul-swallowing oceans. Compared with this, dancing at a funeral was a piece of cake.

Recorded over a year in a church outside Montreal, Neon Bible is a dense and sometimes opaque struggle of faith, with enormous, otherworldly sounds, from bombs to pipe organs, bursting through the bouncy jangle of guitars and accordions. Last time around, Arcade Fire’s combination of eccentric ambition and heart-on-the-sleeve emotion instantly raised the stakes for indie rock. It was no longer enough to mope and sound like Joy Division; you had to overcome something, then sing about it in French with a three-part string section. You can only discover fire once, though, so instead of a revolutionary blueprint, Neon Bible makes a triumphant clamor that’s nearly as cathartic.

Butler is an ingenious nightmarist, dreaming up myriad forms of death and disintegration. In “Black Mirror,” he wanders a nighttime shore like a zombie, finding nothing but a cold, uncaring void. “No moon, no pale reflection,” he reports, with a muted piano-guitar stomp like a more timid version of the Velvet Underground’s “I’m Waiting for the Man.” In the stark, acoustic “Windowsill,” the bad dream becomes an explicit political metaphor, as the Mideast crusade of Canada’s southern neighbor becomes everybody’s unwanted problem: “Don’t want to fight in a holy war,” Butler sings with jittery conviction. “Don’t want to live in America no more.” What could be worse? A wicked, heartless religion that offers no salvation. “Not much chance for survival,” goes the creaky title track, “if the neon bible is true.”

The real savior is music. For every image of horror, every “ocean of violence” or “great black wave in the middle of the sea,” there is a fantasy of escape set to a buoyant bass line. The anxious “Black Mirror” is followed by “Keep the Car Running,” a sprightly clap-along with twinkles of strings and mandolin that puts Butler a couple steps ahead of the dark agents pursuing him. On two of the most powerful tracks, “Intervention” and “My Body Is a Cage,” a booming organ comes along just in time, helping the band turn despair into mighty cries that can “lift you up and take you out of here.” The string arrangements, always the band’s trump card, reach stirring heights, with the brass players of Calexico joining on “Ocean of Noise” for a coda of lush, waltzy grandeur.

Butler, Régine Chassagne (his wife, who pushes her soprano to fairylike levels of weightless sweetness) and their menagerie of pickers and fiddlers walk a tricky path between the self-effacing smallness of indie rock and cosmic-struggle bombast. Almost 30 years ago, U2 carried their invincible optimism on music that was itself boundlessly optimistic; like gospel, its goal was to give strength to belief, to persuade by passionate exhortation. Arcade Fire follow in that quest, but by emphasizing the arduousness of the journey, they make reaching the destination even more joyous. No wonder U2 walked onstage during their Vertigo 2005 Tour to Arcade Fire’s most rapturous song, “Wake Up,” and embraced them as an opening act.

The best thing about spiritual rock is that it’s still rock. “No Cars Go,” the album’s most exhilarating song, imagines a place untouched by the evils of the world: no wars, no black waves, no neon bibles. “We know a place where no planes go/We know a place where no ships go,” Butler and Chassagne sing in spunky harmony, as sheets of electric guitar invigorate them on their pilgrimage. “Don’t know where we’re going,” Butler hollers, but once the roaring choir appears, swelling victoriously, it’s clear they’ve already gotten there.

Download: “No Cars Go,” “Intervention,” “My Body Is a Cage”