The archbishop of Minnesota's two biggest cities argued that the devil is to blame for the legalization of marriage equality in the state, Minnesota CityPages reported on Friday.

"Sodomy, abortion, contraception, pornography, the redefinition of marriage, and the denial of objective truth are just some of the forces threatening the stability of our civilisation," Rev. John Nienstedt said in a speech to the Napa Institute Conference in August. "The source of these machinations is none other than the Father of Lies. Satan knows all too well the value that the family contributes to the fabric of a good solid society, as well as the future of God's work on earth."

Video of the speech, which Nienstedt referred to as his "politically incorrect Powerpoint," was posted by the institute online on Tuesday. The speech was originally delivered on Aug. 2, a day after the state began granting marriage licenses to same-sex couples.

European LGBT news site Pinknews reported that the speech was also republished in Legatus Magazine, the in-house publication for Legatus, which bills itself as "a membership organization for top-ranking Catholic business leaders."

In 2012, Nienstedt -- the archbishop for Minneapolis and St. Paul -- was an outspoken supporter of Amendment One, a bill that would have restricted marriages in the state to unions between a man and a woman, sending letters to priests in the area outlining the church's backing of the measure.

"The reality is that marriage is not ours to redefine, just as another human life is not ours to take,” the archbishop continues," Nienstedt argued in the letter. "God is both the author of life and the author of marriage. It is this most fundamental understanding of the natural order that animates who we are as Catholics."

The measure was defeated at the ballot in November 2012. Gov. Mark Daynton legalized marriage equality in May 2013, and the state began issuing same-sex marriage licenses three months later.

Watch Nienstedt's speech to the Napa Institute, which it posted on YouTube on Tuesday, below.