But then Genesis are not here for the agnostics. With no new product to punt, they play Eighties hits (Invisible Touch, Turn It On Again) alongside more unlikely Seventies bits (Ripples, Firth of Fifth) and rarely announce the names of any of them.
Here in Düsseldorf they were slow to warm up. Rutherford was tentative on Land of Confusion and In the Cage, outplayed by his second banana, Daryl Stuermer. Banks's garrulous keyboards crowded out the guitars, leading to a sound that sat soupily between Chester Thompson's drumming and Collins's confident vocals.
We may have fallen out of love with Collins's cheeky-chappie persona, but it does the job in a stadium show. Halfway through this date, the one-time Artful Dodger bunged a bit of business into the 1973 hit I Know What I Like (In Your Wardrobe). Playing a tambourine solo on elbows, knees, feet and bald bonce, he finally brought the 35,000-strong crowd into the show. The band followed that with the Gothic camp of their 1983 hit, Mama. The crowd applauded as if Germany had just won the World Cup.
And suddenly these fiftysomething comeback curios felt safe to step out of their comfort zone. They played Domino, a ten-minute tune from the 1986 Invisible Touch album. It was horribly overambitious, thick with vulgar sounds and crude power chords, and there was a preposterous moment when Collins, invisible on stage but magnified on the big screen, appeared to be singing from the middle of the time-space vortex from Doctor Who. Fabulous.
Because if there's one thing Genesis should never be, it's tasteful. You can't have that many chords and time signatures in a show and be tasteful. What you can be is passionate, energetic, imaginative, a five-course feast of music for which not everybody will have the stomach. And when they launched into Los Endos, the instrumental finale from A Trick of the Tail, they did so with a rediscovered conviction that they were on to something that might just matter.
A different band left the stage from the one that took to it almost three hours earlier.
Genesis will never be cool they should never try to be. But when they throw themsleves into their task, this reunion really flies.
© Times Online, by Dominic Maxwell at the LTU Arena, Düsseldorf