Barr also told a Fox News TV host he was worried that an increase in mail-in voting could lead to a contested presidential election in November, sounding in on an issue often raised by U.S. President Donald Trump.
In an interview with conservative pundit Mark Levin, Barr said Democrats had pulled away from classic liberal values and now were akin to the "Rousseauian Revolutionary Party" aimed at destroying the institutions upon which the country was built.
"They're not interested in compromise, they're not interested in dialectic exchange of views. They're interested in total victory," Barr said of the left. "It's a secular religion. It's a substitute for a religion."
The comments come nearly two weeks after a contentious hearing before the House Judiciary Committee in which Barr denied accusations he was doing Trump's bidding by intervening in high-profile cases and sending federal agents into cities.
Barr has come under fire from Democratic lawmakers for sending federal officers to disperse protesters in Portland, Oregon, where some demonstrators have attacked a federal courthouse and others have gathered to speak out against racism and police brutality following the May 25 death of George Floyd.
Barr said police have been unfairly maligned and targeted with violent attacks during nationwide protests, and argued greater attention should be paid to a recent surge in violence in some cities that has led to numerous deaths of Black people.