Mercury Rev, Roundhouse, London

Smiling with beatific rapture and throwing his arms wide open like a man here to save souls, Jonathan Donahue swigs red wine from a bottle as he arrives on a stage lit by candles.

Before the gig is over, Mercury Rev's moon-eyed frontman will have thrown Jesus poses and windmilled at a guitar in crescendos so huge you might fairly describe them as "biblical". The sense of neo-religious ceremony couldn't have been more heightened if he'd brought along the bread and fish.

In lesser hands such a display of pomp might invite ridicule, but the Rev don't fear the flourish, and a sense of occasion isn't ill-fitting for the album they're here to play. Every other band is doing a "play the album" tour now, granted, but Deserter's Songs merits the treatment more than most. Emerging as a thrillingly unlikely anomaly during the post-Britpop doldrums of 1998, it conjured the ghosts of American popular music – from Disney to Tin Pan Alley – for space-rock hewn from private traumas but suffused with sweeping wonder and mapped on to expansive imagery. What's more, its success really did save Mercury Rev, who had previously been loved by a select few, but were at the time sinking amid deluges of drug abuse and financial disaster.

A celebration is welcome then, though that triumphalism initially sits oddly with "Holes", a shimmering revery on damaged creativity that loses its frailty in Donahue's dramatic delivery. Yet grand gestures suit "Opus 40" and "The Funny Bird", desolate accounts of inner turmoil delivered as thunder-squall triumphs of hope against plausibility. As Donahue's wingman Sean "Grasshopper" Mackowiak makes his guitar sound like intimations of the apocalypse, the sense that Deserter's was a last bid for survival from a band that had nothing left to lose is expressed with searing force.

The album's subtleties get a little lost, but a bowed saw adds eccentric colour and a rave-like rush of release sweeps doubts before it on "Delta Sun Bottleneck Stomp". The latter's ecstasies flood into the encores, where "Senses on Fire" and a cover of Peter Gabriel's "Solsbury Hill" offer testimonies to the powers of the receptive imagination. True, neither they nor the crashing "The Dark Is Rising" deal in understatement. But a gig this rousing renews your faith that there's magic in Mercury Rev's fearless methods.