Mr Skinner accused the Anglican Church more generally of being "basically heretics".
"There's only one faith - The Roman Catholic Apostolic Faith - because we go right back in our papal line to Christ. All the other sects and cults are in fact man-made. It doesn't mean we condemn the individuals in them, we simply condemn their teaching.''
He said those responsible for the poster would "certainly burn in hell" if they did not repent.
St Matthew's reverend Glynn Cardy said Mr Skinner had left a message on his answer phone in which he used words to that effect.
Mr Cardy said he was disappointed that there was not more tolerance for differing views in our society.
"They're most welcome to protest, that's fine, they obviously feel strongly about it. I'm just disappointed that the strength of their feeling has led to vandalism.''
The motivation for the poster was to get people to think about the social circumstances Mary faced when she found out she was having a child, he said.
"That she had been accused of having an illegitimate child, that she was a poor, young woman. This was a woman of tremendous courage and faith, she's not a sort of plasticised icon, someone who doesn't have human feelings.''
It is not the first time St Matthew's has caused controversy with its billboards.
Two years ago, it displayed a poster showing Mary and Joseph in bed with the caption: "Poor Joseph. God was a hard act to follow."
The poster provoked so much anger it was defaced several times.
Mr Cardy said the posters were not designed to upset people.
"They're designed to get people talking and communicate a message, and people are talking. Our Facebook page alone has had 21.5 million people come to it, and the comments on there are quite balanced ... there's actually some quite good debates going on on the site.''
Catholic Church spokeswoman Lyndsay Freer told the Herald on Sunday the Catholic Action Group had "absolutely nothing" to do with the mainstream Catholic Church.
"I have been critical of the poster, but the last thing we would want to do would be anything destructive," she said.