Progressive rock fans are fascinating.

The word “progressive” is in the name of the music they purport to love, and yet you’ve never seen a group of people so opposed to progress. If a piece of music isn’t complex enough, or is too pop, or contains too few keyboards, or doesn’t exactly ape 1970s Yes and Genesis, right down to the multi-part suites and serious-arty lyrics, prog fans will trash it.

Especially if that piece of music was made by a band that formerly adhered to all the silly rules. The last band to successfully change the prog-rock landscape was Dream Theater – they made it okay for classic metal and thrash influences to creep their way in. Since then, it’s been all about sounding like Close to the Edge, with a dash of Images and Words.

I’m being overly harsh, I know. But troll the Marillion message boards for half an hour, and you’ll see what I mean. Every new piece of music the band unveils gets picked apart, over-analyzed and stacked up against their previous works. They’re not grateful that this band has been around for 25 years and is still creating the best music they can, they’re outraged that that music doesn’t fit their ideas of what Marillion ought to sound like. It’s too poppy, it’s not poppy enough, there are too many drum loops, there are too few guitar solos, the songs aren’t long enough, and when the hell is Fish coming back, anyway?

It almost makes me wonder if these people like the band at all.

You want another good example? Pain of Salvation. Who are they? PoS is a Swedish band led by a mad genius named Daniel Gildenlow, and lately, they’ve been the target of the prognoscenti.

Gildenlow used to be the golden child – his band’s first four albums followed the prog-metal formula set up by Dream Theater and the like, with staccato rhythms, wailing solos and sweetly melodic passages. Their records are all concept pieces, and to be fair, they’re all excellent, for what they are, especially 2000’s The Perfect Element Part 1. But let’s be honest, it’s a formula. Even DT has become depressingly formulaic – here’s the thunderous metal song with the three-minute guitar solo, here’s the ballad with lush keyboards, here’s the 15-minute epic song with six parts, all delineated by Roman numerals.

So you’d think that any attempt to break out of that rut would be seen as, y’know, kind of progressive, but that’s not the case with Marillion, and it’s not the case with PoS. In 2004, Gildenlow debuted his masterpiece, an album called Be. It’s not so much an album as it is a thesis statement on God and man, full of soundscapes and dialogue, but also full of two dozen musical styles that PoS has never tried before.

Here is “Nauticus,” a lovely low gospel moan. Here is “Pluvius Aestivus,” a gorgeous piano instrumental. Here is “Imago,” a shimmering folk song. And best of all, here is “Vocari Dei,” a collage of answering machine messages to God that, honest, is astonishingly moving. The old PoS style crops up here and there (“Diffidentia”), but the overwhelming majority of this album is a grand exploration of new musical forms, constructed as God would hear them – all at once. The record takes a few listens to absorb, but once it takes hold, it’s amazing.

And it was crucified by the fans. Not enough music, some claimed, as if things like “Nauticus” and “Omni” didn’t count.

There’s certainly a lot of music on Scarsick, the just-released follow-up to Be, but there’s also another dozen things that will send (and have sent) the gatekeepers of prog into a tizzy. Scarsick, at first glance, seems to be a return to the old style, with 10 heavy songs over 68 minutes, but take a look at drummer Johan Langell’s expression on the back cover photo – they’re not serious this time. And as any prog fan can tell you, not maintaining an air of absolute gravity at all times is a cardinal sin. (Not to keep bringing up Marillion, but see the reaction to “Cannibal Surf Babe,” or “Hope for the Future.”)

In addition, this record shows that PoS has not, and cannot, forget the lessons learned while making Be. Even the departure of guitarist Kristoffer Gildenlow (Daniel’s brother) can’t dull the band’s newfound experimentalism – they’re letting everything in, and no style is unacceptable. The first two tracks (“Scarsick” and “Spitfall”) show off a rap-metal influence, but this isn’t Limp Bizkit or Linkin Park – these guys are fantastic on their instruments, even when grinding out a punishing, repetitive groove, and the choruses are unfailingly melodic. “Spitfall” may be the finest rap-metal song I’ve ever heard, in fact.

But that’s it for what I feared would be an album-long stylistic switch, as the band moves on to anthemic balladry with “Cribcaged.” By this point on the album, a theme begins to emerge – Scarsick is about America, and modern society, and about being angry at both. “The only cribs we should care for are the ones we are here for, the ones belonging to our children,” Gildenlow sings, taking aim at the MTV generation. The second half of the song is a list of things Gildenlow can do without, and despite the sweet music behind him, he’s not gentle about it: “Fuck the million-dollar kitchen, fuck the Al Pacino posters, fuck the drugs, the gold, the strip poles, fuck the homies, fuck the poses…”

That’s nothing compared with “America,” the flashy hoedown psycho-pop song that follows, during which Gildenlow savages El Presidente Bush and his empire. His dismissive “It could have been great, America” speaks volumes, and the song itself is a superb ride, complete with banjos and pedal steel guitars one second and a Faith No More vibe the next. It’s awesome, but it’s in no way prog-metal, so guess what: the fans hate it.

And if you think that song raises their bile, you should see what they’re saying on the message boards about “Disco Queen,” the eight-minute monster that closes out the first half. The song exists in some imagined halfway point between Tool and the Bee Gees, catapulting from creepy to danceable in a heartbeat. Over its running time, “Disco Queen” morphs into an ever-building symphony of rage, then trips backward into its Saturday Night Fever coda. The lyrics to the chorus are, “Disco Queen, let’s disco.” Honestly.

It’s the best damn song on the record, and the more serious second half can hardly compete. But give it time to sink in, and side two turns out to be marvelous. “Kingdom of Loss” is another look at the wasteland of modern life, this one half-spoken over some of the most lilting, melodic music Gildenlow has written. “Mrs. Modern Mother Mary” has a hint of late-period Queensryche, while “Idiocracy” brings back the Tool influence, adding synth atmospheres and what sounds to me like a mandolin.

And “Flame to the Moth,” the album’s one screamer, carries the record’s theme forward: “We once had blue eyes, probing the skies, now they are blackened from this modern life…” The song ends with one of the disc’s most haunting passages – all goes to piano, as Gildenlow sings defiantly, “When you bow your heads tomorrow at the world we built today, I want you to remember that I stood my ground and said no…”

Scarsick concludes with “Enter Rain,” 10 minutes of trance-like melancholy that find Gildenlow pleading for rain to come and wash away the scars of the last nine songs. The inner spine tells me that this album is supposed to be part two of The Perfect Element, though I’ve heard that this and the next two will actually make up the sequel. Even so, I can’t see many connections between the former Element and this one, and Scarsick develops its themes well enough to stand on its own as an indictment of modern society, complete with mock-ups and tributes to the music of these wasted times.

So why are people hating it? I’m not sure. It’s true that this album is not as painstakingly crafted or mind-bogglingly complex as some of the band’s earlier works, but it is hundreds of times more interesting for its diversity and its willingness to take chances. More importantly, Scarsick shows Pain of Salvation as a band that continues to evolve, shattering their own formulas and refusing to be what they’re “supposed” to be. And I ask you – is there anything that deserves the term “progressive” more than that?

Next week, who knows, but probably Of Montreal, Menomena, the Apples in Stereo and/or Loney, Dear. And if you’re asking yourself just who any of those bands are, trust that I did too, in some cases, and that you’ll want to tune in.

See you in line Tuesday morning.