By Daniel Burke, CNN Belief Blog Co-Editor Follow @BurkeCNN

(CNN) - Frazier Glenn Cross is a white supremacist, an avowed anti-Semite and an accused killer. But he is not, as many think, a Christian.

Cross, who also goes by the name Glenn Miller, is accused of killing three people - all Christians - on Sunday at Jewish institutions in Overland Park, Kansas.

Authorities are weighing whether to file hate-crime charges against Cross, who is suspected of targeting Jews.

The 73-year-old has espoused anti-Semitism for decades. He also founded racist groups like a branch of the Ku Klux Klan and the White Patriot Party, according to the Southern Poverty Law Center.

Both groups have deep ties to Christian white supremacists.

But according to Cross' 1999 biography, he is an adherent of Odinism, a neo-pagan religion that experts say has emerged as one the most vicious strains in the white supremacist movement.

"The faith’s obsession with genetic purity, racial supremacy and conquering supposedly lesser peoples is a recipe for violence," said Josh Glasstetter, campaign director for the Southern Poverty Law Center.

Cross writes in his autobiography, "A White Man Speaks Out":

I'd love to see North America's 100 million Aryan Christians convert to the religion invented by their own race and practiced for a thousand generations before the Jews thought up Christianity. Odinism! This was the religion for a strong heroic people, the Germanic people, from whose loins we all descended, be we German, English, Scott, Irish, or Scandinavian, in whole or in part. Odin! Odin! Odin! Was the battle cry of our ancestors; their light eyes ablaze with the glare of the predator, as they swept over and conquered the decadent multi-racial Roman Empire. And Valhalla does not accept Negroes. There's a sign over the pearly gates there which reads, "Whites only."

Odin, often depicted with a white beard and long robe, is chief among the Norse gods, whose pantheon includes Thor, the god of thunder, and Loki, the mischief-maker

In 2010, a white nationalist group, the Council of Conservative Citizens, boycotted the movie "Thor" because it cast a black actor, Idris Elba, as a Norse god.

Cross writes in his autobiography, which remains posted on his website, that he has prayed for Odin to spark a race war in the United States.

On Sunday, Cross "appears to have been acting out a violent fantasy, with himself cast as the brave Odinist warrior of his imagination," Glasstetter said.

What the killings at Kansas Jewish sites say about U.S. hate groups

Though Odinism has been appropriated by white racists, most adherents are peaceful, earth-loving pagans (some followers prefer the name "heathen"), said Jonathan White, an expert on religious extremists and a professor at Grand Valley State University in Grand Rapids, Michigan.

An ancient Viking religion, Odinism resurfaced in northern Germany in the 19th century, where Nazis later appropriated its themes and gods.

Odinist mythology "was a bedrock belief for key Third Reich leaders, and it was an integral part of the initiation rites and cosmology of the elite Schutzstaffel (SS), which supervised Adolf Hitler's network of death camps," according to the Southern Poverty Law Center.

Odinism also influenced the creation of the American Nazi Party, which was founded in 1959.

Odinism has lately gained in popularity among white supremacists who believe that Jesus is too peaceful and too Jewish to worship, White said. "It's hard to get a violent god out of Jesus."

The Southern Poverty Law Center warns of a Odinist network run out of a California prison, where Asatru, another neopagan religion with roots in Iceland, has also taken root.

"Racist versions of Odinism and its Icelandic version, Asatru, have become increasingly popular theologies among imprisoned racists and others on the radical right in recent years," said the Southern Poverty Law Center in a 2009 report.

Peaceful neo-pagans, meanwhile, have strongly condemned white supremacists who appropriate their religion.

"I want to say that Frazier Glenn Cross is a monster, and it cannot be denied that he's not alone," said Josh Rood, an expert on Asatru at the University of Iceland. "The prison systems, and the white separatist movements have been bastardizing Asatru beliefs, symbols, and myths for a long time."

However, Rood said, white supremacists form a minority - albeit a loud and violent one - of a peaceful and proudly multicultural religion.

Several mainstream neo-pagan and self-described heathen groups have strongly denounced Sunday's killings and are raising money for the victims.

Cross' own public proclamations of faith seem to have taken several twists.

David Embree, a religious studies professor at Missouri State University, said Cross presented himself as a traditional monotheist when he ran for Congress in 2008.

But when he spoke at Embree's classroom in 2012, his views had apparently changed, the professor said.

"He essentially self-identified as an atheist," Embree said. "The more overtly Christian groups in Southern Missouri have pretty much shunned him."

Cross's second in command at the White Patriot Party, Stephen Miller, is a member of the Christian Identity movement, which claims that whites are the "true people of God."

"Though I shared that particular belief, I did not agree with others," Cross writes in his autobiography.

"Christianity is the second biggest trick the Jews ever played on us," he later writes. "The biggest was legalized abortion!"

White said he sometimes refers to the violent strain of Odinism as "Nordic Christianity" because many American adherents borrow from both in creating their racist ideology.

In his autobiography, Cross blends Christianity and Odinism in describing his ideal funeral.

He writes that he would like to be buried in his White Patriot Party uniform. The music would include "The Old Rugged Cross," the venerable Christian hymn, and "Ride of the Valkyries," an opera piece appropriated for Nazi propaganda.

This is how Cross closes the book: "Praise Odin, pass the ammunition, Sieg Heil, and Heil Hitler!"