Born in Breckenridge, Texas, McNallen developed an interest in pre-Christian Scandinavia while in college. In 1969–70 he founded the Viking Brotherhood, through which he printed a newsletter, The Runestone, to promote a form of Heathenry that he called "Asatru". After spending four years in the United States Army, he transformed the Viking Brotherhood into the Asatrú Free Assembly (AFA), through which he promoted Heathenry within the American Pagan community. He espoused the belief, which he named metagenetics, that religions are connected to genetic inheritance, thus arguing that Heathenry was only suitable for those of Northern European ancestry. A growing membership generated internal conflict within the AFA, resulting in McNallen's decision to expel those with Neo-Nazi and racial extremist views from the organisation. Under increasing personal strain, in 1987 he disbanded the Assembly.
Moving to Northern California, McNallen began a career as a school teacher; during the summer vacations he travelled the world as a military journalist, writing articles for Soldier of Fortune magazine. Concerned by what he saw as the growth of liberal, universalist ideas in Heathenry, he returned to active involvement in the Heathen movement in the mid-1990s, establishing the Asatrú Folk Assembly, which was headquartered in Grass Valley, California. In 1997 he was involved in the establishment of the International Asatru/Odinist Alliance alongside Murray's AA and the British Odinic Rite. He brought greater attention to his group after they became involved in the debate surrounding the Kennewick Man, arguing that it constituted evidence for a European presence in prehistoric America. In the 21st century he became more politically active, becoming involved in both environmentalist campaigns and a group promoting the rights of European Americans.
McNallen is a controversial figure in the Heathen and wider Pagan community. His espousal of right-wing ethnonationalist ideas and his insistence that Heathenry should be reserved for those of Northern European ancestry has resulted in accusations of racism from both Pagans and the mainstream media. Conversely, many on the extreme right of the Heathen movement have accused him of being a race traitor for his opposition to Neo-Nazism and refusal to endorse white supremacism.
McNallen was born in the rural town of Breckenridge, Texas on October 15, 1948 to a family of practicing Roman Catholics. After high school, he attended Midwestern State University in Wichita Falls, Texas. While there, he began to investigate alternative religions, reading about the modern Pagan religion of Wicca and the writings of the occultist Aleister Crowley. In his freshman year of college he read a novel, The Viking, by Edison Marshall, which generated his interest in the societies of pre-Christian Scandinavia. According to him, upon reading this book he "got hooked on the spirit of the North", being attracted to the Vikings by what he perceived as "their warlike nature, their will to power, and their assertion of self". In 1968 or 1969 he dedicated himself to the worship of the deities found in Norse mythology, and remained a solitary devotee of theirs for about two years. He later noted that on initially becoming a Heathen, he went through "a stridently anti-Christian phase", and that while he later mellowed in his opinion of Christianity and Christians, he still believed the religion to be "a faulty faith, a foreign imposition on European soil" which had eroded "our traditional culture" and "done us great damage".
In 1969–70, McNallen founded the Viking Brotherhood, issuing a "Viking Manifesto" in which he stated that the Brotherhood was "dedicated to preserving, promoting and practicing the Norse religion as it was epitomized during the Viking Age, and to further the moral and ethical values of courage, individualism, and independence which characterized the Viking way of life." While the group placed greater emphasis on promoting what McNallen perceived as the Viking ideals — "courage, honor, and freedom" — rather than on explicitly religious goals, in 1972 they gained tax-exempt status as a religious organization from the Internal Revenue Service. In the winter of 1971–72 he began publishing a newsletter, The Runestone, using a typewriter and mimeograph machine; he gained his first eleven subscribers through an advert that he placed in Fate magazine. He initially used the term "Norse religion" to describe the Heathen religion that he was practicing, before later adopting the term "Odinism" from the work of Danish Heathen Else Christensen. He then changed it once again, this time to "Asatru", which he had discovered in Magnus Magnusson's book, Hammer of the North, and subsequently popularized within the American Heathen community.
During his college years, McNallen had been a cadet in the Reserve Officers Training Corps, and on completion received a degree in political science. After completing his college education he joined the United States Army, remaining with them for four years, volunteering for service in the Vietnam War before being stationed in West Germany. Although frustrated at what he described as the "authoritarian stupidity" of the army, it impacted his views on warrior ethics and warrior ideals. He retained his interest in Heathenry while a member of the army, and circa 1974 adopted the belief that there was an intrinsic connection between the Norse gods and humans of Northern European descent. After his discharge from the Army in 1976, McNallen hitchhiked across the Sahara Desert before returning to Europe and then to the United States. There, he settled in Berkeley, California.
On his return to the United States in 1976 he transformed his Viking Brotherhood into the Asatrú Free Assembly (AFA). The sociologist of religion Jennifer Snook described it as "the first national Heathen organization in the United States", while according to the religious studies scholars Michael F. Strmiska and Baldur A. Sigurvinsson, the AFA "established many of the important organizational and ritual structures that remain operative" in American Heathenry into the 21st century. Initially meeting in the backroom of an insurance agency owned by group member Dick Johnson, the group later established a store-front office in Breckenridge, while through the AFA, McNallen continued publishing Runestone and produced booklets on Asatru. He also began conducting religious ceremonies, or blóts, and lectured at Pagan events across the U.S. He established groups known as guilds within the AFA to focus on particular endeavours, such as the Mead Brewing Guild and the Warrior Guild. The latter published a quarterly, Wolf Age, in which McNallen displayed his fascination for warrior ethics.
In the early 1980s McNallen used The Runestone to promote his theory of "metagenetics"; the idea that spirituality or religion was encoded in genetic material and thus passed down to one's descendants. In formulating this concept he was influenced by his reading of Jungian psychology with its concept of archetypes existing within a collective unconscious. Accordingly, he described "Ásatrú as an expression of the soul of our [Nordic] race", and thought that it was a "real mistake" for anyone not of Northern European ancestry to follow Heathenry. Not everyone in the AFA embraced this theory, with it being rejected for instance by prominent AFA member Robert Stine, although it would later be developed in new directions by the Heathen Edred Thorsson. Snook characterized it as pseudoscience.
As membership of the AFA grew, there were an increased number of internal conflicts, often along ideological lines. This was exacerbated by the fact that all affiliated groups, known as kindreds, were autonomous, while the AFA promoted an individualistic ethos which allowed for a diversity of opinions. This generated conflicts at the AFA's annual meetings, or Althings, for instance when Michael "Valgard" Murray—one of the Neo-Nazis within the AFA—threatened to kill a fellow member of the Assembly because he was gay. McNallen did not share these Nazi sympathies, disapproving of the Nazi ideal of a centralized totalitarian state, which he believed was anathema to the Heathen ideal of freedom; accordingly, he sought to push out the Neo-Nazis and other racial extremists from the group. In 1978 he demanded that AFA members be prohibited from wearing Nazi uniforms and insignia at their events. Among those who left the AFA as a result were Wyatt Kaldenberg—who was appalled by what he described as McNallen's "soft stance on race" and "middle of the road" politics—and the Neo-Nazi Heathen Jost Turner, who was McNallen's brother-in-law. McNallen nevertheless remained close to Turner and his family after the division. As a result of such changes, by the late 1970s there was a clear division between McNallen's AFA, which emphasized religious over racial political aims, and Christensen's Odinist Fellowship, which placed far greater emphasis on the latter.
While the autonomous nature of different AFA-affiliated individuals and groups meant that McNallen and his wife Maddy Hunter had little power, they bore the brunt of the responsibility of running the Assembly and organizing its Althings. They were also impacted by a downturn in the Texan economy, with McNallen losing his job as a jail guard. Bankrupt and frustrated, McNallen and the other senior figures in the AFA found that they were unable to organise the group's seventh Althing for 1987. Seeking to ensure that it would continue regardless, McNallen assembled a committee of AFA members, the Southern Heathen Leadership Conference, which issued a document declaring that new membership would be frozen, that AFA responsibilities would be divided more widely, and that McNallen and Hunter should take a vacation from their organizational chores. However, in 1987 McNallen shut down The Runestone and dissolved the AFA altogether, relocating to Northern California. However, according to Strmiska and Sigurvinsson, the AFA had "planted seeds that would take strong root". As a replacement for the Assembly, Murray established the Asatru Alliance, which organised the eighth American Althing for Arizona in June 1988.
In 1986–87, McNallen worked as a peace officer in Stephens County Texas sheriff's office jail and Sheila kept books for an oil company. In 1986, he and Sheila moved to a semi-deserted mining town in the mountains of California, and there he earned teaching credentials before teaching science and mathematics at a junior high school for six years. During his summer vacations he travelled abroad, during which he met with guerrilla groups active in various parts of the world, writing articles about them for magazines like Soldier of Fortune. He later related that this experience convinced him of the need for ethnonationalism and ethnic separatism across the world. McNallen also joined the U.S. National Guard and was called up during the 1992 Los Angeles riots.
In the mid-1990s, McNallen returned to an active involvement in the U.S. Pagan scene, aided by his new partner, Sheila Edlund. They established their own Heathen group, the Calasa Kindred, which they affiliated to Murray's AA. Dissatisfied with what he perceived as the increasing domination of Heathenry by "liberals, affirmative-action Asatrúers, black goðar, and New Agers", he decided to re-establish the AFA in 1994, this time calling it the Ásatrú Folk Assembly. This group based its headquarters in Grass Valley, and was structurally very similar to the old AFA, reviving McNallen's The Runestone publication, albeit in a yearbook format. The AFA served much the same constituency as the established AA, with religious studies scholar Jeffrey Kaplan believing that its purpose in the Heathen community was therefore largely superfluous. Seeking to promote Heathenry to a wider audience, McNallen also established the Ásatrú Community Church, which held Sunday services twice a month in the community room of the Nevada County Library; he later acknowledged that it was not particularly successful.
During the 1990s, McNallen befriended the prominent Heathen Michael Moynihan, later recommending and selling Moynihan's journal Tyr on the AFA's website. McNallen and the AFA also appear to have cordial relations with the racial extremist Ron McVan, co-founder of Wotansvolk, publishing some of McVan's writings in Runestone. When in the 1990s, Christensen was arrested for drug smuggling, McNallen teamed up with Murray to form a defense fund for her. In September 1997 he was a signatory to the foundation of the International Asatru/Odinist Alliance (IAOA), a global union of folkish Heathen groups, alongside Murray of the AA and Heimgest of the British Odinic Rite; they were later joined by representatives of the French and German branches of the Odinic Rite, before the union terminated several years later. The alliance convened an international meeting, or Althing, every three years. In 1997, McNallen married Sheila Edlund at the seventeenth Althing, held in Utah; the ceremony was officiated by Murray. In 1999, the AFA purchased land in the higher Sierra of Northern California, there establishing a space where Heathen kindreds could meet together to practice their religion.
In keeping with his ethnonationalist beliefs, McNallen endorsed a 1993 Declaration of War Against Exploiters of Lakota Spirituality, expressing the opinion that white people should resurrect the religions of their European ancestors rather than adopting the belief systems of Native Americans. However, he came into conflict with Native American communities over the discovery of Kennewick Man, a prehistoric skeleton unearthed in Washington State; while local Native communities viewed the body as one of their ancestors and sought its repatriation to them, McNallen argued that it was Caucasian. In October 1996 the AFA filed a suit in the U.S. District Court of Portland to prevent Kennewick Man being given to the Native communities under the Native American Graves Protection and Repatriation Act (NAGPRA); the court ruled that the human remains were not "Native American" within the meaning of NAGPRA. McNallen expressed the view that Native American communities wanted to prevent forensic testing of the Kennewick Man's body because they feared that it would prove that he had been Caucasian, thus establishing that there had been a Caucasian presence in the prehistoric Americas. He believed that Caucasians had entered the Americas via the Bering Strait at around the same time as the ancestors of the Native Americans did, but that the Caucasians were subsequently wiped out; he warned that "that can happen to us too" and thus steps should be taken to preserve the existence of North America's European population. In 2000, the AFA withdrew from its involvement in the Kennewick Man legal case, stating that it had run out of funds to continue. The publicity surrounding the case nevertheless brought the AFA to far greater attention.
During the late 1990s, the AFA began promoting what it termed "tribalism", encouraging Heathens to form networks of extended families to help secure the religion's future. By mid-2001, McNallen and other figures in the leadership felt that they were again overworked and overstretched and so tried to reduce the group's hierarchical structure by abandoning the concept of membership. In the 21st century, the AFA made significant inroads online, establishing a homepage, blog, podcast, online radio, as well as accounts on Facebook and YouTube. Around the same time it began to promote the writings of Nouvelle Droite authors such as Alain de Benoist, selling an English-language translation of the latter's Being a Pagan on its website.
In 2009 McNallen was invited to the International Asatru Summer Camp, but this was opposed by many of the groups attending, who argued that he should not be invited because of what they perceived as his racist views; a number of European Heathen groups, such as Norway's Bifrost and the Swedish SAS, threatened to boycott the event as a result of McNallen's invite. In 2011, the AFA sent a contingent to the annual conference of a white nationalist organization, the National Policy Institute, in what some figures close to McNallen revealed was an attempt to recruit members. After this incident was publicized it resulted in accusations of racism being levelled against McNallen and the AFA from various parts of the Pagan blogosphere.
At the turn of the 21st century, McNallen decided to embark on more specifically political activity, becoming President of the European American Issues Forum, a group devoted to advancing the rights of white Americans of which he had been a longstanding member. However, finding the job stressful and afflicted with colon cancer, he later resigned from the presidency. In December 2012, McNallen created the Facebook page Green Asatru to promote environmental ideas within Heathenry. In June 2013 McNallen started the non-profit organization, Forever Elephants, to combat ivory poaching in Africa, using Facebook to promote this cause. In 2014, he retired from his possession as a juvenile corrections officer, where he had been employed for the previous five years. In 2015 he published Asatru: A Native European Spirituality; it was reviewed by the religious studies scholar Jeffrey Calico for The Pomegranate: The International Journal of Pagan Studies, in which he noted that the book was "an important moment" for the Heathen movement, being "comprehensive and expansive, touching thoughtfully on numerous important aspects of the faith". Calico also noted that McNallen "clearly has his legacy in view throughout this book, apparent in the self-referential tone that occasionally surfaces." In 2016 McNallen stood down as head of the AFA, and was replaced by Matt Flavel, Allen Turnage, and Patricia Hall.
McNallen believes in an integral link that connects one's genetic heritage to one's religion. He has expressed the view that his AFA exhibits the "middle ground on racial issues. On the one hand we were proud of our European heritage, and we actively espoused the interests of European-descended peoples. On the other hand we opposed totalitarianism and racial hatred, convinced that decency and honor required us to treat individuals of all racial groups with respect." Although he has attempted to evade the "Nazi-Odinist identification", he has "expressed sympathy with what he sees as the "legitimate frustrations of white men who are concerned for their kind". He has penned articles on what he fears is the coming extinction of the white race, arguing that in the United States, white people will be largely replaced by Hispanics, with the concomitant demographic shift resulting in a decreased political influence for the country's white population. According to Snook, McNallen's concerns reflect "white American resentment of a perceived loss of status and privilege in modern, multicultural society in particularly divisive political times." She added that a repeated element of his argument, the presentation of white people as victims, was common throughout white supremacist discourse.
McNallen does not consider himself to be a racist, insisting that his support for racial separatism does not necessitate a "dislike, much less hatred" for other racial groups. However, in May 2015, the magazine Vice published an article in which it accused McNallen of being a racist who manipulated ancient Norse beliefs "for his own hateful devices". Conversely, many in the extreme racialist wing of Heathenry have accused McNallen of being a race traitor because he has not unequivocally endorsed white supremacist and Neo-Nazi perspectives; they have commented negatively on his "refusal to work for the survival of the Aryan race" and accused him of promoting "cowardly PC politics".
The religious studies scholar Jeffrey Kaplan stated that McNallen's politics "fit comfortably into the right wing of the political spectrum", although added that in the Heathen community McNallen "suddenly becomes very much the man of the centre – and is thus a legitimate target for both sides." The historian of religion Mattias Gardell characterized McNallen as a libertarian. McNallen rejects the descriptor "conservative", expressing the view that there is little in modern Western society worthy of conserving. McNallen envisions a future stateless American confederacy based on ecologically sustainable, decentralized tribal groups. He has also expressed support for all ethnic separatist movements across the world, including those of the Tibetan, Igbo, Karen, and Afrikaner people. This has attracted criticism from the racial extremist wing of the Heathen community, who have claimed that it detracts from the focus on the white or Aryan struggle against other racial groups. According to Katja Lane, co-founder of the extreme racialist Wotansvolk, McNallen is "promoting everything BUT the Aryan cause." However, in writings and YouTube videos, Stephen McNallen has spoken favorably of Wotanism and the Fourteen Words, networking with Red Ice TV, a social media outlet of the Alt Right. In early 2017, the Asatru Folk Assembly updated its Declaration of Purpose. The primary change in the document was "Northern European Folk" being changed to "Ethnic European Folk" with an indication in text of that meaning white people.