Michael Moore stands in front of Trump Tower with provocative sign

The 61-year-old filmmaker, known for his Oscar-winning documentaries and anti-capitalist rants, later took to Facebook to describe, in a scathing letter to Trump, why he’s taking him on.

“Here we are in 2015 and, like many other angry white guys, you are frightened by a bogeyman who is out to get you. That bogeyman, in your mind, are all Muslims. Not just the ones who have killed, but ALL MUSLIMS,” Moore wrote, after recalling the first time he and Trump met while appearing on a talk show together in 1998.

According to Moore, Trump’s controversial proposal to bar all non-American Muslims from entering the U.S. was fueled by “desperation and insanity.”

He continued, equating the belief that “we are all children of God” to the assertion that “we are all Muslim.”

“I was raised to believe that we are all each other’s brother and sister, regardless of race, creed or color. That means if you want to ban Muslims, you are first going to have to ban me. And everyone else,” Moore wrote.

“If you don’t like living by these American rules, then you need to go to the time-out room in any one of your Towers, sit there, and think about what you’ve said,” he adds.

Moore included a photo of himself standing in front of Trump Tower in New York City holding a sign that read “We are all Muslim,” and encouraged his supporters to post similar photos of themselves on social media using his message as a hashtag.

“I will post all the photos on my site and send them to… Mr. Trump,” he wrote.

At press time, a majority of the images posted to Twitter accompanied by Moore’s hashtag were gruesome photos of radical Islamic terrorists displaying their victims or edited versions of Moore’s own photo in front of Trump Tower.

Moore’s Facebook post, however, garnered nearly 420,000 “likes” and 23,000 comments less than 24 hours after being posted.