Driven by its staunch opposition to Donald Trump, The Atlantic has endorsed Hillary Clinton for President of the United States, marking just the third time in the magazine's 160-year history that it has made a presidential endorsement.

Labeling the Republican presidential nominee "a demagogue, a xenophobe, a sexist, a know-nothing, and a liar," The Atlantic's editors encouraged their readers to "act in defense of American democracy and elect his opponent."

The last time The Atlantic took sides in a presidential election was in 1964, when it sided with Lyndon B. Johnson due to similar fears about his opponent, Barry Goldwater. Its only other presidential endorsement came 104 years earlier when it backed Abraham Lincoln.

"The Atlantic does not have a tradition of weighing in on presidential contests except when there is perceived to be a danger to the Republic," Jeffrey Goldberg, the Atlantic's national correspondent and the man who wrote the first draft of the endorsement, told CNNMoney.

"The founding manifesto of The Atlantic was that it would be 'the organ of no party or clique,'" Goldberg continued. "We adhere to that. Only when a candidate is so obviously dangerous, or so obviously unqualified for the job, does The Atlantic decide to weigh in."

The Atlantic's endorsement comes less than a week after USA Today, the most widely circulated newspaper in the nation, published an editorial encouraging its readers not to vote for Trump because, it said, he lacks "the temperament, knowledge, steadiness and honesty that America needs from its presidents."

Related: USA Today urges voters to oppose Trump

While the impact of presidential endorsements by media outlets is subject to debate, both endorsements are notable coming from news organizations that have resisted partisan classification.

Unlike USA Today, The Atlantic's endorsement does encourage readers to vote for Clinton. It acknowledges, though, that it is "mainly concerned with the Republican Party's nominee, Donald J. Trump, who might be the most ostentatiously unqualified major-party candidate in the 227-year history of the American presidency."

Goldberg said no single issue influenced The Atlantic's decision, but rather that it was the result of Trump's overall record, character and temperament.

"The evidence accumulated over time," he said. "This is not a normal election and Trump is not a normal candidate."