The question raises the issue of whether religion should continue to shape public law in an increasingly secular and pluralist society. Laws relating to sex — concerning marriage, contraception, homosexuality, and consent — have long reflected religious moral codes, especially those derived from Christianity. Yet modern societies increasingly define justice in terms of autonomy, equality, and harm prevention rather than divine command. The key issue, then, is whether moral authority should remain rooted in theology or instead rest on rational, secular grounds accessible to all citizens. Utilitarianism, through Bentham and Mill, strongly supports the separation of religion from law, grounding legislation in reason and human well-being rather than in revelation. By contrast, Natural Law and post-secular thinkers such as Durkheim, Habermas, and Taylor maintain that religion continues to provide essential moral cohesion and guidance. This essay will argue that religious teachings should have no further role in shaping laws relating to sex, because secular, rational ethics are better suited to protecting liberty and pluralism in a diverse society.

Jeremy Bentham provides a powerful philosophical foundation for removing religious influence from sexual law. His utilitarian ethics, based on the principle of utility — that the right action is the one which produces “the greatest happiness for the greatest number” — rejects all appeals to divine command or natural law. Bentham viewed religious moral codes as sources of unnecessary suffering, describing them as “nonsense upon stilts” when used to justify legal coercion. In his private manuscripts on sexual ethics, Bentham condemned laws criminalising homosexuality and other consensual sexual acts, arguing that they produce pain without preventing harm. For Bentham, pleasure and pain are the only valid measures of moral value, and the law’s function is to maximise the former and minimise the latter. Religious interference in sexual legislation thus violates both reason and justice, since it restricts harmless pleasures out of superstition. Laws against contraception or same-sex relations, for example, inflict pain through guilt and punishment without increasing happiness or social welfare. Bentham’s secular utilitarianism replaces divine authority with empirical calculation, insisting that moral and legal reasoning must be open to all rational agents regardless of belief. The separation of church and state is therefore not merely political but ethical: it ensures that law serves human well-being, not theological conformity. Critics might object that Bentham’s hedonism risks moral relativism, allowing any pleasure to justify action. Yet Bentham’s consistent application of the harm principle safeguards against exploitation: where there is no harm, there is no ground for prohibition. In this sense, Bentham provides a compelling philosophical basis for excluding religious teaching from sexual law, ensuring legislation is grounded in measurable human welfare rather than metaphysical speculation.

John Stuart Mill extends and refines Bentham’s argument by linking secular law to individual liberty. In On Liberty (1859), Mill articulates the harm principle: “the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others.” Mill’s utilitarianism is qualitative rather than quantitative — distinguishing higher pleasures of intellect, love, and moral development from mere sensual gratification — but his political philosophy is firmly secular. He explicitly warns against the “tyranny of the majority,” including the moral tyranny of religious majorities imposing their views through law. For Mill, the role of law is not to enforce moral virtue but to protect personal autonomy and the freedom to pursue one’s own conception of the good life. Religious teachings, being based on faith rather than universal reason, have no rightful authority in determining law for all citizens. In sexual ethics, this means that laws should regulate only matters of consent and harm, not sexual morality itself. For instance, Mill would oppose laws restricting same-sex marriage or reproductive rights on religious grounds, since these violate individual liberty without preventing harm. At the same time, Mill does not advocate moral nihilism: he recognises that society depends on moral education and self-restraint, and that religion may continue to influence individuals privately. However, he insists that such influence must remain within the realm of persuasion, not coercion. Law must be neutral among competing moral doctrines, safeguarding the liberty necessary for moral and personal growth. Thus, Mill strengthens the case for excluding religion from sexual law: only a secular framework, grounded in harm and autonomy, can ensure both justice and freedom in a pluralistic society.

A contrasting view, however, comes from Natural Law and from post-secular sociological thinkers who argue that religion continues to play a vital role in maintaining moral order. Thomas Aquinas held that human law derives its legitimacy from natural law, itself a participation in divine reason. Laws are just only if they accord with this higher moral order. From this perspective, sexual ethics cannot be detached from religious teaching, since human sexuality has a divinely intended purpose: procreation and the unitive bond of marriage. Modern Natural Law theorists such as John Finnis defend this in secular language, identifying basic human goods — including procreation, friendship, and community — which the law should protect if it is to carry universal, rational authority. Religious teaching, on this account, articulates objective moral truths about human flourishing so that excluding religion from law risks making that law unjust and to quote St Augustine “not really law at all”. Post-secular thinkers such as Émile Durkheim, Jürgen Habermas, and Charles Taylor extend this argument sociologically. Durkheim saw religion as the expression of the collective conscience, binding societies together through shared moral norms. This suggests that the law and religion should be saying the same thing in articulating a value consensus, even if religion should not directly influence or dictate what the law is. Further, Habermas argued that in a “post-secular” age, secular and religious citizens must engage in dialogue, translating moral insights from faith into public reason. Taylor likewise maintains that secularism should ensure fairness between worldviews, not simply banish religion from the public sphere. Together, these perspectives challenge strict secularism: if religion helps sustain moral consensus, its exclusion might weaken the moral foundations of law. However, this counterclaim can be rebutted by questioning the practicality and justice of grounding law in religious or natural-law reasoning in an increasingly plural society. The assumption that there is a single, knowable moral order is untenable in contexts of religious diversity and moral disagreement. Programmatic secularism argues not for hostility to religion, but for its restriction to the private sphere, where it may shape personal conscience without constraining public law. Habermas’s call for dialogue can be preserved within this framework: religious citizens may express moral concerns publicly, but the laws themselves must be justified in secular terms accessible to all, avoiding the privileging of any faith tradition. Moreover, attempts to legislate moral order on religious grounds often produce the very social divisions they seek to prevent — as seen in conflicts over reproductive rights and marriage equality. The pluralism of modern societies requires laws grounded in reason, consent, and human rights, not theological anthropology. Religious teachings may continue to guide believers, but they cannot serve as the foundation of public law without undermining equality and freedom. Thus, while religion may contribute to moral discourse, its direct role in shaping sexual law should end.

In conclusion, religious teachings should indeed have no further role in shaping laws relating to sex. Bentham and Mill demonstrate that secular, rational principles of harm and utility provide a clearer and fairer foundation for legislation than appeals to divine command. Although Natural Law and post-secular thinkers highlight religion’s continuing moral and cultural value, in a plural and democratic society law must be justified to all citizens through reason alone. The best reason for this is that secular law protects both freedom of conscience and the integrity of religion itself, preventing faith from becoming an instrument of coercion. Religion may still inform private morality and public dialogue, but it must no longer determine the content of sexual law. In a society of many faiths and none, the only just foundation for law is the shared language of human reason.