In June 2013 I surveyed Australian Presbyterian ministers about same-sex “marriage”, and most thought that the definition of marriage in our Commonwealth Marriage Act would change within the next five years. Five years is now looking sanguine.

This confronts us with a serious issue. Ministers are registered as marriage celebrants under the Act. And so if things keep going the way they are, we will become registered celebrants of a different definition of marriage from the one we are registered under now. What should we do if and when the legal rug is shifted beneath our feet?

Before we get to that question, we should review the arguments against same-sex marriage, which are many and plain and well known:

First, it implicitly sanctions homosexual practice, which is explicitly condemned in the Bible (Lev. 18:22; 20:13; Rom. 1:26-27; 1 Cor. 6:9-10; 1 Tim. 1:10; Jude 1:7).

Second, it perverts Jesus’ definition of marriage: “For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh” (Mat. 19:5).

Third, it undermines the God-given family structure: one man and one woman with any children that they have conceived, or adopted.

Fourth, it breaks the prima facie right of children to know, and be raised by, their natural parents. The right to marry is a compound right, which includes the right to bear children. A homosexual couple can only procure children with the assistance of a third-party gamete donor. This means conceiving children with the prior intention of removing them from either or both of their natural parents. This is manifestly unjust, and contradicts the U.N. Convention on the Rights of the Child (1990).

Article 7 of that convention says: “The child shall be registered immediately after birth and shall have the right from birth to a name, the right to acquire a nationality and, as far as possible, the right to know and be cared for by his or her parents.” And Article 9 states: “A child shall not be separated from his or her parents against their will, except when competent authorities subject to judicial review determine, in accordance with applicable law and procedures, that such separation is necessary for the best interests of the child.”

Recently a number of Australian parliaments have apologised for forced adoptions, not only to mothers, but also to the children who were taken unnecessarily from their parents. Perversely, same-sex marriage legislation will normalise the very practice condemned by these apologies.

Donor-conceived children are also beginning to rail against the injustice of this practice. Numerous painful testimonies are recorded in chapter 6 of the 2011 Australian Senate report Donor Conception Practices in Australia, as well as the Anonymous.Us.org project.

Fifth, it will open the Pandora’s Box to other perversions of marriage, including polygamy, polyamory, and incestuous marriages.

Sixth, it will strengthen the attack on religious freedoms. The moment same-sex marriage laws were passed in New Zealand, the Charities Commission notified the Family First Christian lobby group that it would be deregistered and lose its tax-exempt status, because it promotes “a point of view about family life that does not have a public benefit, (including) the view that the union of a man and a woman through marriage is the fundamental social unit.”

Seventh, it mutilates one of the clearest and most beautiful pictures of the Gospel. Many Christians say that they won’t protest against same-sex marriage because “it is not a gospel issue”. But God gave marriage to be a picture of the gospel (Eph. 5:25-27), and so a perversion of marriage is a perversion of the gospel.

Same-sex marriage is an immoral institution that will bring incalculable harm to our nation. That’s why we must pray hard that our political representatives will not succumb to it (1 Tim. 2:2), and tell them why we think it is wrong.

In any case an altered Marriage Act will advocate a particular view about marriage and sex and family. If it is changed to accommodate the practice of homosexual relationships, same-sex parenting, and third-party donor surrogacy, then it will reflect the legitimisation of these practices. Social legitimacy is in fact a core reason why homosexual activists want same-sex marriage.

And so what should our ministers do if marriage is redefined to embrace the evils of same-sex marriage? The survey showed that most intend to retain their registration and go on marrying people “as normal”, so long as they are not compelled to “marry” same-sex couples. They draw a line not at the point of redefinition, but at the point of compulsion.

In August I wrote a paper for General Assembly of Australia 2013 arguing that we ought to resign our marriage registration at the point the law is changed. There are two aspects to my argument.

On the one hand, although I may feel that I can maintain my registration without personally endorsing the evils endorsed by the Act, how will this not cause outside observers to assume, by my formal allegiance, that I think the changed Act is acceptable?

No gospel minister is compelled to register under the Marriage Act. It is something we freely choose to do. If you freely join the St Kilda Football Club, then you should expect to be seen as a supporter of that club. Likewise it is impossible to see how a freely registered marriage celebrant of the Marriage Act would not be counted as someone who endorses the Act.

And so in Quadrant in June 2013 Christopher Akehurst argued that, in the event of marriage redefinition, Christian ministers should “withdraw from acting as a delegate of the state in conducting wedding ceremonies. To continue to do so would imply ... acceptance of the new state-imposed definition of marriage”.

If this scenario parallels that of “eating meat sacrificed to idols” in 1 Corinthians 8, and I think it does, then love would compel us to give up our freedom to conduct marriages under a changed Act, so as not to “become a stumbling block for the weak”, and so as not to “wound their weak conscience” (1 Cor. 8:9,12).

On the other hand, Christians must not only not commit evil, we must not even associate with evil. If a redefined Marriage Act represents the legitimisation of the evils of homosexual practice, same-sex parenting, and third-party donor surrogacy, then as a Christian I will want nothing to do with it, and will separate myself by resigning my celebrant’s registration. As Psalm 26:4 says, “I do not sit with deceitful men, nor do I consort with hypocrites; I abhor the assembly of evildoers and refuse to sit with the wicked.”

How then will I marry people? In many nations, such as Singapore and France, Christian couples register their union with a civil servant for legal purposes, and then get married by a minister in a worship service. This is what I intend to do if the Marriage Act is changed. I would allow the couple (Christian or not) to register at a government office, and then I would conduct a Christian wedding service. I should add that I would not require a couple register at a civil office. For they may well feel that by doing so too are endorsing the Marriage Act and the evils it will represent. I would leave this decision up to them.

In any case, I am urging my brother ministers to form the same intention to resign from the Act if it is redefined. Like baptism, we can use our own rites, keep our own records, and issue our own certificates. We would do this for the ultimate good of marriage and family, and for the reputation of Jesus’ church and His gospel.