Scott Marsh painted the mural, titled The Happy Ending, on the wall of the Botany View Hotel in Newtown in support of same sex marriage on Wednesday night.

Within hours, white paint had been spattered over George Pell's face. Then, on Thursday night, the mural was painted over with black paint.

A video posted on Facebook by Bryan Butterfield showed a man painting over the mural while a small crowd watched on and criticised him. Butterfield said three "religious dudes" arrived at the Botany View Hotel to paint over the mural.

"They have threatened staff and patrons," he wrote. "[They] are here to cover up a 'hateful' painting while spreading hate and fear in the process. Try and get that logic."

In the video, a woman asked one of the men: "Do you have to come and see this if it's offensive to your eyes? Do you live across the road?"

"It's Australia, I'm free to do whatever I like," he responded. "And when I do want to come here, I don't want to see this."

"Don't look at it!" the woman responded.

3 dudes have shown up to paint over the latest Scott Marsh mural at the Botany View Hotel tonight, in their protest against it. They have threatened staff and patrons, these staunch religious eshays are here to cover up a ???hateful' painting while spreading hate and fear in the process. Try and get that logic. On top of this the phones have been ringing non stop with threatening and prank phone calls while people from all over Australia bombard the Facebook page of the venue with one star reviews. I thought these sort of people were memes, had no idea they actually exist.Posted by Bryan Butterfield on Thursday, 16 November 2017

The pub had faced a backlash from Christians and offended members of the public and Marsh said staff had taken the phone off the hook due to incessant, abusive calls.

Overnight, Marsh posted a screenshot of a text message from a friend who said his housemate saw "Christian dudes" painting over the mural.

The mural featured Mr Abbott in a wedding dress and sash with the words "Bride to be" next to a shirtless and muscular Cardinal Pell. Mr Abbott was depicted with one hand down Cardinal Pell's pants.

Marsh said on Wednesday it was intended as a satirical piece in support of same sex marriage, and that he didn't mean to target anyone's religion.

"I'm conscious of people's religions, I tried to make it about George Pell. That's why I didn't include any religious iconography."

Marsh said he included the clerical collar and zucchetto (cap) to make it clear it was Pell pictured, but avoided other Christian symbols.

On Wednesday, a member of the Christian Lives Matter Facebook group posted a photo of the mural, calling it "disgusting".

The post called on members to complain to the pub and leave one-star reviews on its Facebook review page.

"How can we as a society accept this persecution of Christians and allow them to mock our clergy," it said.

Hundreds have since left poor reviews on the pub's Facebook page, which has become a battleground, with many supporters of the pub commenting on, and disputing, one-star reviews.

White and beige paint was thrown over Cardinal Pell's face on Wednesday. It is not known who defaced the mural.

"It is what it is," Marsh said. "I try not to get too upset about those things."

However, he said he was disappointed he didn't get a chance to "get a nice photo in the morning light".

Marsh is the artist behind a number of controversial Sydney murals including one on a Redfern wall in September, showing Mr Abbott marrying himself.

Despite the backlash, Marsh said most of the feedback he had received had been positive.

"The response has been 98 per cent positive; the only negative response has been from a few Christian groups," he said.

Following the first incident of vandalism, Marsh said he planned to leave the defaced mural as it was.

"I think it's just a chapter in the life of the mural," he said.

"When you're making public art, the reaction is important, the reaction is needed."