Weatherly's reference to adoption is apt, since the British government passed anti-discrimination laws in 2007 that prohibit adoption agencies from refusing to adopt children to same-sex couples. These laws were met with protest from Catholic adoption agencies in particular, some of which have since chosen to comply.

Another noteworthy case featured a Christian couple with a good track record as foster-parents who lost their approval as carers after the High Court found that their "traditionalist" religious views on homosexuality could conflict with the welfare of foster children. As the couple in question protested: "We are prepared to love and accept any child. All we were not willing to do was to tell a small child that the practice of homosexuality was a good thing."

Many people are understandably concerned about these attempts to drive religious groups from the public square, or to make them conform to moral principles they cannot accept. But these signs of growing intolerance to moral diversity are part of a deeper change that is inevitable and will be beneficial in the long run, as society is forced to take ethics seriously once more.

Let me explain: for about sixty or so years, Western culture has been engaged in a protracted rebellion against whole swathes of public ethics. For whatever reason, our culture has effectively disdained to engage in moral debate on subjects that pertain primarily to matters that prick the individual conscience, or invoke personal moral responsibility.

Ethical reflection has instead been consumed with 'big picture' social issues, the kinds of moral problems that fall upon whole societies to remedy: class struggle, poverty, and disadvantage; racial prejudice, civil rights, and institutionalised racism; gender equality; environmental issues; the problem of nuclear weapons and disarmament. Of course the individual plays a role, but his efforts are fruitless without profound social and cultural change.

Issues such as abortion were subsumed into the greater struggle for women's rights, eclipsing the traditional ethical discourse that had long held abortion to be intrinsically immoral. This situation is now typified in the infamous conclusion that abortion is a private matter, and should not be subject to public ethical debate.

Abortion is only the most obvious example of how personal ethical issues can be removed from the public domain under the auspices of protecting individual freedom. Individual freedom is the 'big picture' moral imperative that justifies the present culture's disdain for those who attempt to 'moralise' over personal choices.

In the debate over voluntary euthanasia we again see a "personal choice" pitted against the alleged religious paternalism of those who attempt to apply traditional ethics to the question of euthanasia, without regard for the prevailing theme of individual freedom.

Likewise, on the issue of sexual orientation we have been advised to keep our personal values to ourselves and allow others to live their own lives without fear of judgement or discrimination. Let others enjoy their individual freedom.

As an ethicist, I find the status quo intellectually disappointing. Tolerance might seem like a social panacea, capable of neutralising all conflicts and overcoming all evils, but in principle it merely calls an uneasy ceasefire in the implicit ethical battle underway in our society. It's all very well to say: "Don't like abortion/gay marriage/euthanasia? Don't have one." But an objective ethical question remains unanswered: are these things good for us, as human beings?

What we are finding, at last, is that the ideal of unbounded individual freedom to make morally neutral choices just cannot satisfy human nature. We need to believe that we are doing what is right, even if we shy away from words like "good" and "right". It is entirely reasonable that in a culture demanding tolerance for same-sex relationships under the auspices of individual freedom that some would take the next logical step and declare their same-sex relationship to be, in fact, "good". Not just a private good to be enjoyed under the rubric of tolerance and individual freedom, but a good which ought to be recognised and affirmed as such by the whole community.

Same-sex marriage advocates are seeking not merely the legal and financial rights that go with the institution of marriage, but the social affirmation that marriage promises. To put it another way, some same-sex marriage advocates have argued that the existing marriage laws are inherently discriminatory and promote homophobia within the broader community.

Either way, we are well beyond the point of "tolerance". The examples from Britain show that our society is beginning to embrace the ethical implications of its official stance on issues such as sexual orientation. The High Court rejection of the Christian foster-carer's appeal, the anti-discrimination laws' interference in the operation of Catholic adoption agencies, and now the first hints of similar action with regard to same-sex marriage, show a growing appetite for public ethical engagement in hitherto private matters. If religious organisations are forced to choose between their moral teachings on same-sex marriage and their legal right to perform marriage at all, then we will for the first time in many years face a genuine public confrontation between competing ethical theories, without the soothing refrains of tolerance and individual freedom.

In short, some of those who once called for tolerance and individual freedom have adjusted to the success of their programme and decided to shift the boundaries. But their new goal cannot be achieved by appealing to tolerance, freedom, or even diversity because they now seek to impose their own implicit moral system upon the whole of society.

Attacks on the legitimacy of religious institutions in areas of marriage and adoption correspond to increasing pressure to override the right to conscientious objection for doctors and other healthcare professionals. This new appetite for moral coercion signals the end of tolerance, the end of a pretence that we could "live and let live" without reaching binding moral conclusions.

What was once illicit became tolerable; now the merely tolerable has been normalised. But, as tolerance comes to an end, so will the illusion that moral diversity is truly a viable long-term strategy for a society. We might begin again to ask in earnest what is good and evil in human life.

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Zac Alstin works at the Southern Cross Bioethics Institute in Adelaide, South Australia.