Why This Couple Will Divorce If Same-Sex Marriage Is Legalised

A couple from Canberra have vowed to get a divorce and end their "sacred" 10-year union if Australia allows same-sex couples to legally marry.

Nick Jensen and his wife Sarah have no intention of separating and hope to have more children.

They believe widening the definition of marriage to include same-sex couples threatens the sacred nature of the union and leaves the door open to polygamy.

Mr Jensen wrote in an article published in Canberra CityNews that they are prepared to divorce.

"My wife and I, as a matter of conscience, refuse to recognise the government's regulation of marriage if its definition includes the solemnisation of same sex couples," said Mr Jensen, who is director of the Lachlan Macquarie Institute, which partners with the Australian Christian Lobby to offer scholarships designed to develop a Christian worldview and foster leaders in government policy.

Mr Jensen said he and his wife entered into their marriage "as a fundamental order of creation, part of God's intimate story for human history, man and woman, for the sake of children, faithful and for life".

"And so, if later on in the year the state does go ahead and changes the definition of marriage and changes the terms of that contract then we can no longer partake in that new definition unfortunately," he said.

Legalising same-sex marriage would undermine "our most sacred institution, and have serious consequences for children who would grow up without a mother or father," Mr Jensen said.

He also feared that recognising same-sex couples would mean that the definition of marriage could be expanded even further.

"Once you say that marriage is detached from children, [that it's] just about love, then when three people come to the state and say 'well we're all in love', then the state has no grounds, except unjust discrimination, to say why they can't get married," he said.

"When it becomes detached to the child's right to a mother and a father and the sacred institution that it is, then suddenly it becomes meaningless and those boundaries can't be put back in place," he said.

The move is in stark contrast to high-profile celebrities who have vowed not to marry until gay marriage is legalised.