A Republican state lawmaker has admitted that he wrote a manifesto for a holy war that calls for supporters of gay marriage to be murdered.

Rep. Matt Shea, a pro-Trump Republican who represents the 4th district in the Washington state House of Representatives, on Wednesday admitted that he wrote four-page document, titled the “Biblical Basis for War.”

The manifesto outlines a plan for a Christian “holy army” to conduct a biblical war against non-believers, carrying out a “census of all able bodied males” aged 18 to 45.

The men would be required to agree to the army’s “terms of justice and righteousness,” which state: “Stop all abortions; No same-sex marriage; No idolatry or occultism; No communism; Must obey Biblical law.”

Those who agree “must pay share of work or taxes,” the document explains, before adding: “If they do not yield – kill all males.”

The document was published by the Spokesman-Review after being leaked by associates of Shea. It is unclear when precisely the document was penned.

Spokane County Sheriff Ozzie Knezovich told the Spokesman-Review on Wednesday that the document was “a ‘how to’ manual consistent with the ideology and operating philosophy of the Christian Identity/Aryan Nations movement.”

Knezovich was given the document in August, and “gave it straight to the FBI.”

The FBI and Joint Terrorism Task Force told KHQ that the document is being reviewed.

Shea, a strong opponent of LGBT+ rights, uploaded a Facebook Live video after the Spokesman-Review broke the story, claiming the story was planted by the “Marxist and Islamic counter-states” to discredit him.

He then admitted writing the document, claiming it was “a summary of a series of sermons on biblical war in the Old Testament as part of a larger discussion on the history of warfare.”

Shea added: “This document, in and of itself, was not a secret. I’ve actually talked about portions of this document publicly.”

However, several of the candidate’s donors have requested refunds in the wake of the revelations, according to the newspaper.

A spokesperson for Northwest Credit Union Association, which gave $1,000 to Shea’s campaign, told Spokane Public Radio that it had requested the return of the donation because “his beliefs do not reflect the views and values of our organisation, member credit unions or customers.”

Shea is up for re-election in November 6’s midterms, facing Democrat Ted Cummings.

Cummings wrote on Facebook: “This man does not represent my views and I am embarrassed that he is my current representative.

“Eastern Washington is top great for fear and hate! Let’s vote this man out of office!”

His campaign added: “Matt Shea supporters want their money back, meanwhile there has been a steady stream of donations all morning to his challenger. People all across the state and nation are saying NO to hate!”

Shea has held the seat since since 2008, winning re-election every two years.

The candidate did not face a Democrat opponent in 2008, 2010 or 2014.

In 2012 and 2016, the only elections where he has faced a Democratic opponent, Shea won the district with 56 percent and 64 percent of the vote respectively.