Mawyer, who founded the nonprofit Christian Action Network in 1990, once worked as editor-in-chief of the Moral Majority Report, published by the evangelical fundamentalist Rev. Jerry Falwell, according to CAN's website.
Based in Lynchburg, Va., CAN describes itself as a public advocacy and education organization "based on biblical principles, values, traditions and American ideals." The website says it uses documentaries, radio and TV interviews, books and alliances with other organizations "to impact change."
The lawsuit claims that Mawyer has appeared on the Fox News shows "The O'Reilly Factor" and "Hannity" as well "Entertainment Tonight" and NBC's "Today" show, where "he continues spreading various sensational, erroneous theories and presents them as fact."
The group claims that Mawyer and CAN have spent the past decade "waging excessive divisive and intolerable attacks against the plaintiff."
The Muslims of America was organized in the mid-1980s around congregations that sought to escape big-city problems in the countryside, according to the complaint.
The group says it selected 60 acres in Hancock, N.Y., about an hour southeast of Binghamton, along the Delaware River's border with Pennsylvania, as "a safe haven for American Muslims to raise families while establishing a peaceful community free from harmful elements such as those occurring in the inner cities."
Hancock is identified as the group's principal place of worship, although other communities were established elsewhere. Twelve now exist in seven states, Canada and Trinidad, according to the complaint.
The community in Hancock, called Islamberg, has about 30 families.
Mawyer posted an article on the CAN website in November 2012 listing Islamberg's address and "daring" doubters to its existence to "go see it for themselves," the complaint states.
That put residents in danger of "vigilantism and violence," according to the complaint.
"The basis of defendants Mawyer and CAN's attacks against plaintiff center on their bold, public and false campaign alleging that plaintiff is a murdering, thieving terror organization and runs terror training camps," the complaint states.
The complaint includes a litany of defamatory allegations attributed to the defendants. For example, page 230 of the "Twilight" book allegedly states that "MOA had been listed on the State Department's list of terrorist groups but was removed in the year 2000 after what appeared to be a period of inactivity."
Muslims of America says it "was never listed on the State Department's list of terrorist groups."
The back cover of the book states: "In the privacy of Muslim compounds across our land they are preparing our own citizens to launch a holy war - jihad - against America. As many state and federal authorities turn a blind eye, these Islamic extremists convert our own citizens, then teach them how to kill," the complaint states.
The plaintiffs say, "This entire statement is false and defamatory."
Citing page 27 of the book, the complaint continues: "The women suffer a dismal fate, enslaved to their men and forced into polygamous marriages, forced to have as many children as possible, sometimes beaten and raped, all under the banner of religious submission to Islam and the stifling rules of MOA that women must endure."
This entire statement too is false and defamatory, the group says.
Citing page numbers, the group claims the book accuses it, falsely, of "creat(ing) an independent army of jihadists who have been killing their own countrymen for decades" and of "host(ing) an array of notorious characters in the jihadist world."
It claims that Mawyer posted this statement on his CAN website: "My book details the nearly 30-year history of MOA in America with its crimes, its acts of terrorism and its bold claim to establish Islamic guerrilla training camps across the country."
Mawyer also falsely accused Muslims of America of ties to Beltway sniper John Malvo, and of threatening Mawyer's life, according to the complaint.
The group claims that someone fired 13 shotgun blasts into a Muslims of America village in Red House, Va., on Dec. 29, 2012.
Muslims of America demands at least $3 million in damages for defamation and libel, and an injunction, gag order, restraining order and costs.
It is represented by Tahirah Clark of Deposit, N.Y.