Ex-Vatican ambassador, Pope Francis critic calls Harris 'infernal monster'

"In this election you must choose between two radically opposed ways of conceiving the government of your Nation: you are called to choose between democracy and dictatorship, between freedom and slavery," Vigano wrote.

Vigano wrote that while Trump has "serious problems in his positions" on abortion and assisted procreation, the former president aims to protect the "fundamental freedoms of citizens."

Vigano called Harris "an infernal monster who obeys Satan," arguing that in her America, Catholics and Protestants "are considered fundamentalists to be marginalized and eliminated, and their children are considered the property of the State."

"Trump's America can become great and prosperous again," he wrote. "Harris' America is destined for invasion and for moral, social, and economic destruction: the most ferocious dictatorship."

Trump, Vigano argues, is "committed to freeing America" from what he called the "tentacled grip" of the so-called "deep state."

Vigano served as the Vatican's ambassador to the United States, also known as the Apostolic Nuncio, from 2011 to 2016.

Catholics historically voted for Democrats until the 1960s and early 1970s, when crime and cultural issues came to the fore alongside economic concerns.

Today, Catholic voters are evenly split between the two parties, and whichever side captures the majority is usually the side that wins the White House.

Fox News Digital's Chris Pandolfo contributed to this report.