Metal has such a cozy relationship with the infernal that it's easy to assume it really is all about the devil, just like mama always said. But I'd argue that the real fascination isn't with hellfire but rather with eschatology and omnipotence, and that you can make music that sounds like the end of the world without putting your money on the number of the beast--if the devil is heavy, after all, it stands to reason that God is even heavier. Isis plays metal as radiant and exalted as a celestial palace or a sunlit glacier--it's serene, forbidding, beautiful, and of course enormously, crushingly awesome, sometimes by turns and sometimes all at once. (And as any good theologian will tell you, "all at once" is enough to make the devout shit themselves.) Led by guitarist and vocalist Aaron Turner, who also runs the Hydra Head label, Isis started out back in 1998 with the brutally focused tech grind of the Mosquito Control EP, but by the recent Panopticon (Ipecac) they had evolved into something much harder to classify--a metal band that somebody thought would make a fine warm-up act for Tortoise. Justin Broadrick's current project, Jesu, would be a better match, but I can see the logic behind tonight's bill: like Tortoise, present-day Isis has an abstract, disciplined, grown-up sound, shaped by monkish patience and restraint. The vocals are distant and dispassionate when they're not entirely absent, the towering pillars of guitar are tastefully gilded with electronics, and the epic, incantatory songs are totally divorced from verse-chorus structure. Thankfully these guys still know how to rock the fuck out like the good Lord intended--they begin "In Fiction" by stacking layer after layer atop a simple rhythm for five and a half minutes, so that when they finally deliver a headbanging riff it feels so good you want to cry. This show is part of Flower 15; for a complete schedule see page 38. Sat 11/12, 11 PM, Metro, 3730 N. Clark, 773-549-0203 or 312-559-1212, $16, 18+.