The billboard, which has been twice put up and pulled down as many times by vandals "lampoons literalism and invites people to think again about what a miracle is", say church leaders at St Matthew-in-the-City in Auckland.
"Is the Christmas miracle a male God sending forth his divine sperm, or is the miracle that God is and always has been among the poor?" they posed.
In the illustration, a dejected Joseph looks down as a sad Mary, lying next to him, looks upward. The caption, meanwhile, reads: "Poor Joseph. God is a hard act to follow."
"It is intended to challenge stereotypes about the way that Jesus was conceived and get people talking about the Christmas story," church leaders explained.
Not surprisingly, the church has come under fire and drawn remarks from all around the world – not only for the billboard, but also for its ridicule and misrepresentation of conservative Christians, who St Matthew's vicar Glynn Cary describes as fundamentalists.
The church has been called out for its liberal theology, which includes support for openly gay church leaders and a questionable understanding of Advent.
"For fundamentalist Christians, the incarnation is about the miraculous arrival of a baby soon to die and by his blood save us," said Cary in a sermon last Sunday. "For progressive Christians, the incarnation is about the miracle of this planet earth and all life that exists here."
Despite St Matthew's controversial billboard and views, some have praised the church for getting people to think about God during the Christmas season and to think "outside the box".
"We have had lots of wonderful response from people for whom this billboard gave them reason to hope that maybe there was 'room in the inn' of Christianity from them. Or at least with us out the back," Cary reported Saturday.
And even the large volumes of negative feedback the church has received has been viewed by the church in a positive light.
"Our purpose in putting up this billboard was five-fold," explained Cary on Saturday, listing the first purpose as being to invite people to think about the virgin birth and the nature of God.
"Point one was hugely successful," he reported. "Whether people agreed with our theology or not, conversations broke out all around the world in work places, homes, and schools."
Since the billboard was put up outside the church, the church's website has received over 67,000 hits. The billboard itself, meanwhile, has been pulled down twice.
Though the church replaced the first billboard, following the second act of vandalism, the church decided not to replace it a second time "due to concerns for public safety".
"It has been widely reported on the internet that we took the billboard down due to pressure from those who object. This is not the case," church leaders reported Sunday.
The church also reported Sunday that it is looking to post sermons inspired by the billboard on their website, www.stmatthews.org.nz.
"St Matthew's already suspects and already has some evidence that our billboard has inspired a few sermons this Christmas season," they stated. "In the interest of furthering the conversation we are offering to post sermons on this topic."
Though the church's pews have room only for 200, St Matthew church leaders say their "congregation" comprises all those who are connected to them through the web as well, including the more than 1,500 regular visitors to their site.
The church also serves as a meeting place for a LGBT congregation and a Buddhist meditation group.
St Matthew is affiliated with the Anglican Diocese of Auckland.