It is also why people of religious convictions whose religion holds that marriage is to be only between a man and a woman should do the same.

Let me explain. Being married, bankrupt, a child, insane or under sentence affects a person's legal status. It makes them legally different from other people, with different legal rights and obligations. True, marriage is voluntary, whereas childhood, insanity and being under sentence are not. Bankruptcy often is not, though it can be.

But the important point is that changes in status happen through the operation of law and events. The law should apply equally to all.

True, ministers of religion almost automatically receive the power to solemnise marriages, but only if their religious denomination is recognised by the Marriage Act and they are on a register kept under the act, and when they solemnise a marriage they must do so in accordance with the minimum requirements of the act even if they add extra bits from their religion.

So all house-of-worship marriages in Australia take place through the operation of law, not religion.

A minister may refuse to solemnise a marriage or make it conditional on the parties complying with religious tests (such as not being divorced), but it is always open to people who are refused a religious ceremony to have their marriage solemnised by a civil celebrant.

In France, the legal and religious are sensibly separated. You must have a civil ceremony before a state official, however brief, before the law recognises you as married. After that, you can have whatever religious ceremony you like.

When a person changes status from unmarried to married, a whole lot of legal rights and duties change, too – those with respect to each other and those with respect to the couple and the world at large.

Many on the "no" side, such as Tony Abbott, argue there is no need for same-sex couples to marry because all the discriminatory legal provisions against unmarried couples (whether of the same or different sexes) have been removed. These are things like access to a partner's superannuation, their estate upon death, their financial support upon splitting up and so on. Let's call them couple rights.

But the Abbott argument is untrue. For a start, couple rights are created upon the instant of marriage, irrespective of how long the couple have known each other. Couple rights for unmarried people emerge only after a period of cohabitation. More importantly, many of them are enforced through state and territory courts.

Further, because some couple rights for unmarried people emerge only after a period of cohabitation, there is a deal of uncertainty about enforcement and recognition. This is especially true in medical next-of-kin situations: who gets notified, who makes decisions if someone is unconscious, etc. A marriage certificate makes it much clearer.

There is legal inequality and legal exclusion if couples of the same sex are denied access to marriage certificates that make these couple rights certain and instantaneous upon marriage.

But let's say it were true that unmarried same-sex couples had all the legal rights of married couples and no impediments that married people do not have. That could only leave some purely non-legal element to marriages confined by Commonwealth law to people of different sexes – that is, a religious element.

One might then ask whether the present restriction of marriage to members of opposite sexes is a law "for imposing a religious observance", which is offensive to section 116 of the constitution. That is probably a long bow.

Nonetheless, the denial of marriage rights to people of the same sex (given that everything else is supposedly equal) appears purely a historic religious and cultural relic.

Surely, equality before the law in Australia is now more important than historic religious and cultural beliefs. Laws about status should apply equally to all. You become an adult, a bankrupt or a convict under sentence according to a set of rules and events that apply equally to all, not according to your sexual orientation.

In South Africa during the apartheid years, South African law provided for another status that affected a person's legal rights, prohibitions and duties: race. Among those rights and prohibitions, of course, were rules about whom you could legally marry. To illustrate the point further, in present-day Myanmar, the marriage rights of the Rohingya people are restricted.

Human equality before the law, and therefore human dignity, should take priority over marriage. If there is to be no marriage equality, there should be no marriage law at all; no status of "married" or "not married". People would need to rely on contracts. But at least everyone would be equal before the law.

Non-fundamentalist religious people also could easily recognise the importance of equality before the law. Their religious beliefs may well oppose marriage by people of the same sex in their house of worship, and other people of no religion or a different religion may well accept that as part of freedom of religion and freedom of association.

Fundamentalists (of any religion) believe everyone should follow their religion, but non-fundamentalist opponents of same-sex marriage within their houses of worship could easily accept same-sex marriage outside them as part of equality before the law.

In the next few weeks, if this is the only way to get our parliamentarians to do their job and to do the right thing, grit your teeth, hold your nose, fill out the survey and send a clear message to the tail that wags the government dog that human equality and dignity transcend religious conviction or notions of tradition or societal "cohesion". Cohesion lies in equality before the law. Decency lies in equality before the law. Religious belief should be separated from that.

crispinhull.com.au