A man who attacked an Auckland church billboard depicting the Virgin Mary holding a positive pregnancy test has defended his actions.

The $300 Christmas billboard was erected by the St Matthew-in-the-City Church last week to raise discussion about Mary's circumstances coming into Christmas.

Catholic Action Group member Arthur Skinner was caught, and later admitted to, slashing the board with scissors yesterday in protest.

Skinner held a congregation with Catholic Action Group supporters outside the church this morning to explain why he did it.

''Yes it's vandalism and if they want to arrest me then be my guest,'' Skinner said. ''If it comes to that, I believe in being persecuted for my faith.

''We don't look for trouble but watch out when you start this sort of thing.''

Skinner said there are half a million Catholics in New Zealand who were outraged about the sign.

''The politicians should be getting into this church and saying 'you cannot do this','' he said.

Skinner said the sign didn't depict what the church had intended it for.

''Some people dont see this as how it should be seen - as a blasphemy, pure and simple,'' he said.

Skinner said if the church replaced the billboard he would rip it down again.

Elizabeth Skinner, 17, was among the group which attended the meeting outside the church.

''We're here to say the rosary and reparation for the blasphemous image of our lady up here,'' she said.

''This is making a comedy of her and she is not an object of comedy.''

Elizabeth said the action group had called the church and left messages but had received no reply about the sign.

St Matthew-in-the-City vicar Glynn Cardy said he was disappointed the sign had been slashed but didn't believe he would be pressing charges.

''I'm disappointed that there is not more tolerance of different views,'' he said.

''Obviously the person who pulled it down has different views than mine and and other Christians but I would have hoped for a world where we can tolerate different views about Mary, Christianity and God.''

Cardy said a replacement $300 sign would need to be discussed.

''We need to think about replacing and talk with our team of people.''

Cardy said he didn't have a problem with the protesters gathering outside the church on Sunday morning.

''They obviously feel strongly about it - I'm just disappointed that strength of feeling has lead to vandalism.''

Cardy said he had received a lot of public feedback about the billboard, which was designed to create discussion.

''People are talking, our Facebook alone has had 21.5 million people come to it and the comments are quite balanced,'' he said.

''The touching ones are women who have been in a similar circumstance and [they] say 'hey I know what that is like' and we've had a few of those which are very moving.''