It seems inconceivable that some 28 years ago in California a little-known psychedelic Jewish musician and his wife gave birth to Adam Pearlman, who would become one of America’s most notorious traitors in the war on terror. This Southern California boy has emerged as a leading instigator of a religious war between Christians and Jews on one side and the Muslim world on the other.

News outlets reported on September 8 that a sealed indictment accused Adam, now known as Al Qaeda operative “Azzam the American,” of helping the terror organization with communications and propaganda, serving as an English translator, and providing information about American culture and vulnerabilities. Treason charges are pending.

In 2004, at the age of 26, Azzam was first put on the FBI’s most wanted list; his aliases included Abu Suhayb Al-Amriki, Abu Suhayb, Yihya Majadin Adams, and Yahya. He reportedly received training in Afghanistan terrorist camps, and Newsweek reported that he was sent by the mastermind of the attacks of September 11, 2001, Khalid Sheik Muhammad, on a mission to join a suicide attack outside Baltimore.

In time for the fifth anniversary of September 11, Azzam appeared on Al-Sahab — the press and broadcast production house of Al Qaeda and its main propaganda vehicle — attacking America as the “Zionist-Crusader-Fascist” entity. The majority of his speech was a verbal assault on Christianity, which he called a “hollow shell of a religion, whose followers cling to an empty faith, and a false conviction of their inevitable salvation.”

Azzam was given the honor of being introduced by Al Qaeda’s deputy leader, Ayman al-Zawahiri, in the September 2 tape, and directed his speech “To America and the rest of Christendom.” “Anyone who pays any attention to the messages of the leaders of the jihad, like Sheik Osama bin Laden and Sheik Ayman al-Zawahiri … will know that they have been consistent in inviting the Americans and other unbelievers to Islam. …We would prefer that all Americans and all the other unbelievers … accept the truth. Islam encourages us to invite even the most obstinate enemies and give them a chance to repent,” he said.

Adam Pearlman’s religious journey began when his family converted to Christianity and took the last name Gadahn. He first came in contact with Islam when his father slaughtered goats and sold the meat to Muslim halal markets. As a pimply, head-banging teenager, Adam embraced Islam at an Orange County mosque when he was just 17.

Until this summer, an essay by “Adam Pearlman” was posted on the University of Southern California’s Muslim Student Association compendium of Muslim texts; it has been quoted widely in the press. Titled “Becoming Muslim,” it states: “As I began reading English translations of the Qur’an, I became more and more convinced of the truth and authenticity of Allah’s teachings. … Having been around Muslims in my formative years, I knew well that they were not the bloodthirsty, barbaric terrorists that the news media and the televangelists paint them to be.”

In October 2004, with his face covered, Azzam appeared in his first Al Qaeda video and declared, “Allah willing, the streets of America will run red with blood.”

Azzam’s next video, again with his face covered, was aired on Al-Jazeera on September 12, 2005, “Four years after the blessed raids on New York and Washington, we find the people of the West continuing to speculate about the … historic events. … We find them uncertain about which steps or actions they must take to achieve the restoration of the security they once enjoyed,” he said.

He explained that the numerous audiotapes, videotapes, and communiqués Al Qaeda has issued since September 11 “have been released to explain and propound the nature and goals of the worldwide jihad against America and the Crusaders and convey our legitimate demands.”

Azzam was not heard from again until July 8, when counterterrorism officials said he had moved up in rank within Al Qaeda and was now a key official behind Al-Sahab’s operations. He appeared in a video for the first time without his mask, alongside footage of the London suicide bomber Shehzad Tanweer and Mr. Zawahiri, and warned: “When we bomb their cities and civilians … no sane Muslim should shed tears for them.”

Some counterterrorism analysts have downplayed Azzam’s warnings and other English-language messages directed to his fellow Americans on behalf of Al Qaeda.

However, as they include what is commonly referred to in different periods of Islamic history as “the triple choice” — conversion, death, or submission — they should be taken seriously. These are all issues that could be identified as markings of further attacks against America.

Mr. Stalinsky is the executive director of the Middle East Media Research Institute.