Who was Akhnaten? For composer Philip Glass, this mysterious Egyptian pharaoh, said to be Queen Nefertiti’s husband and the father of King Tutankhamen, was a rebel-hero. In the 14th century B.C.E., Akhnaten defied tradition by attempting to forge a monotheistic religion, and even tried to change Egyptian artistic culture by moving the capital city and building a new one, Amarna, now a ruin.

Glass’ 1983 opera, “Akhnaten,” the last in his trilogy of portrait operas — the others are “Einstein on the Beach” and “Satyagraha,” about Gandhi — was given its West Coast premiere by Long Beach Opera (LBO) at the Terrace Theater on March 19. A repeat performance is scheduled for March 27.

Speaking by phone from New York, Glass projects an undiminished enthusiasm for “Akhnaten.” “You could go into the Metropolitan Museum and see this very weird-looking dude,” Glass recalled, referring to androgynous representations of the pharaoh.

“Akhnaten did something that no one else had done. He flew in the face of a completely traditional society that worshipped the past, and he tried to change it. And, of course, 17 years later [the period of Akhnaten’s reign], they killed him.”

Whether counterrevolutionary powers had Akhnaten assassinated has never been proven, but evidence shows they did try to destroy his memory. “Akhnaten had a short, but very dramatic life,” Glass said. “His name was erased from the list of kings. They vilified him to such a degree that they wanted to eliminate him from their own history.”

It is tempting to politicize the Akhnaten story, as Achim Freyer did for the world premiere in Stuttgart, Germany, in 1984, with the bad guys who overthrow Akhnaten dressed in leather and stomping around the stage in jackboots. And, a few months later, David Freeman’s American premiere for the Houston Grand Opera took a more overtly sexual and literal approach, with sexy dances, an Oedipal subtext (Akhnaten’s mother is a bombshell) and tons of sand brought on stage to evoke Egypt.

The efficient LBO production avoided such political-sexual angles on this historically and metaphorically loaded story, conveying instead a timeless, almost floating, quality. In terms of dress, Akhnaten’s androgyny is only suggested. Counter-tenor Jochen Kowalski wears a white jacket and pants with some skirtlike material draped around him. And video designer Frieder Weiss’ tastefully phantasmagoric images are refreshingly free of Egyptian visual clichés — no mummies, pyramids or sand.

Not that going full Egyptian on the set and costume design is anathema to Glass. The composer, in Atlanta a few years ago for what he thought would be a concert version of “Akhnaten,” suddenly found himself faced with the mother lode of Egyptian clichés.

“When I got there, they discovered a storage room with all the Egyptian costumes and sets from an old production of ‘Aida,’ ” Glass recalled. “And they said, ‘Why don’t we just do the opera with them and see what happens?’ ”

Glass was wary. “Because ‘Aida’ is one of the most widely performed operas in the repertoire, everybody has to deal with this Egyptian kitsch.” But the “Aida”-ized “Akhnaten” turned out well. “It looked great,” Glass said. “You didn’t think of it as kitsch at all, because the music wasn’t. The music took you to a certain place. It was kind of funny, because it was a really traditional ‘Aida,’ but it worked.”

For LBO’s artistic and general director, Andreas Mitisek, “Akhnaten” needed “a totally different approach” than that of a regular opera. “It’s a highly stylized work, as Egyptian art was,” Mitisek said. “There is metaphorical imagery that you can interpret as being related to Egypt, but the further you stay away from being too literal, the more you can portray the timeless meaning of the story.”

Shalom Goldman, a professor of Hebrew and Middle Eastern studies at Emory University, who worked on the Egyptian, Akkadian and Hebrew texts of “Akhnaten,” sees the pharaoh as a figure of both myth and history, like Gilgamesh, Alexander the Great and Cleopatra.

“He lives on in the mythic imagination,” Goldman said, “which may not dovetail exactly with the strict historical description. He is important to scholars, adventurers and romantics, because Egyptians wiped out his name, destroyed his statues and buried his city. In the 1880s, parts of the city were discovered. For thousands of years, nobody knew about this guy.”

Goldman said Akhnaten started to become a cultural hero in the West around 1904. And by 1937, in “Moses and Monotheism,” Freud was speculating that the monotheistic ideas of the Hebrews may have come from Akhnaten.

“Because the Hebrews were slaves in Egypt, it would be natural to think so,” Goldman said. In the opera’s centerpiece, Akhnaten sings a “Hymn to the Sun,” based on a text said to be either written or authorized by him. “And then the chorus sings in Hebrew from Psalms about the glory of God. So that’s where we’re suggesting that in the ancient world, these ideas could go underground for a while and then resurface again.”

But was Akhnaten really the first monotheist?

Goldman, who also teaches a “Discovering Ancient Egypt” course at Emory, said that’s no longer accepted as fact. “He simplified the Egyptian religion,” Goldman said. “He took it down to one god, symbolized by the sun. It’s not quite the monotheism of a transcendent god in some other dimension. Rather, Akhnaten said there’s a god on earth, and I’m his human manifestation. And you need to worship him through me.”

For Goldman, the portrait of Akhnaten in Glass’ opera is not inaccurate. “Though there is now more uncertainty about it, some of this is academic fashion — a portrait of the past gets constructed, and a new generation feels that it is its job to ‘deconstruct’ the work of their intellectual forebears.”

Glass said the Akhnaten story has become “part of our collective unconscious”; then he corrected himself. “I would say it’s part of our collective conscious, because it’s not unconscious. Somehow, by really good luck, my ‘Akhnaten’ fell into the wake of this big ship, which is Egyptology, and got swept into some kind of, well, I would say, respectability almost.”

“Akhnaten.” March 27, 2 p.m. $25-$110. Long Beach Opera, Terrace Theater, 300 E. Ocean Blvd., Long Beach. (562) 436-3661. longbeachopera.org.

Rick Schultz writes about music for the Los Angeles Times and other publications.