From the 1960s until quite recently, British historians have frequently used the term ‘secular’ in their own writing, on the assumption that the meaning of this term is widely-understood and obvious. But actually, there are at least three quite different uses of the term ‘secular’ in modern Western history, and we need to get them distinct if we’re to make any analytical headway. Indeed, these differences are crucial for understanding secularity, secularization, and modern European political culture.

The Medieval Christian usage

The modern Western term ‘secular’ comes from the Latin ‘saeculum’, which originally meant ‘a long period of time’, but eventually shifted to mean ‘of this age’ (as opposed to ‘the world to come’), and then to mean ‘of the world’. In the middle ages, the paired terms ‘religious’ and ‘secular’ referred to types of clergy: ‘religious clergy’ were those who worked in monasteries, and ‘secular clergy’ were those who worked outside them, in ‘the world’.

The post-Medieval Christian usage

At the same time, though, Western Christendom had always distinguished between two halves of the Christian polity: the Christian state, responsible for earthly matters, and the Christian church or churches, responsible for eternal matters. In the early modern period, the paired terms ‘religious’ and ‘secular’ came to refer to this two-fold division of authority. So ‘religious’ meant ‘to do with the churches’, and ‘secular’ meant ‘to do with the state’. At the same time, though, European polities were all still Christian (at least until 1789) – it was just that they distinguished between these two spheres of authority, between the political leadership, and the moral leadership.

So, in this Christian usage, one can speak of ‘secular authorities’, to mean people in the government (rather than in the church); and ‘secular intellectuals’ to mean people working in non-religiously-affiliated universities (rather than in theological colleges). In this usage, these people could still very easily be Christians; it’s just that they’re working in the ‘temporal-concerns’ bit of the Christian polity, rather than the ‘eternal-concerns’ bit.

Many non-monotheistic cultures, by contrast, do not bifurcate moral duty in this way. In the secular Soviet Union, for example, the political leadership was also the moral leadership: there were not two sets of institutions, and two sets of hierarchies, political and religious; these were combined into a single politically supreme and morally authoritative Communist Party hierarchy.

Finally, and crucially: in this Christian framework, the invented domains of ‘the religious’ and ‘the secular’ are distinct, but they are also partners. The assumption is that, in Christian polities, the religious sphere and the secular sphere will continue to co-operate for as long as the Christian polity survives. Of course, Western political reality was much messier than this: medieval, early modern and modern European history is full of Christian disputes about where exactly the religious/secular boundary should lie, such that Church or State gains jurisdiction over a particular question. But co-operation is how it’s supposed to work in theory.

The secular usage of ‘secular’

The secular usage of ‘secular’ is quite different. In this usage, the terms ‘religious’ and ‘secular’ do not refer to components of the same Christian polity, but to two completely distinct moral cultures, one belonging to ‘Traditional’ cultures, the other belonging to Modernity. ‘Secular’ here means ‘has departed from religion, is not religious at all, now gains morality from non-religious sources’. So, in this usage, we can speak of ‘secular society’ meaning ‘a society that has irreversibly abandoned religion’. Being ‘secular’ in this sense is a subset of being ‘non-religious’: it means (a) not being ‘religious’, but also (b) being more modern than ‘religion’. The secular use of the term ‘secular’ is positing a chronological contrast between the two – hence the insistence on irreversibility.

In this usage, ‘religion’ and ‘the secular’ are opposites, and so they’re inversely related: the more you have of one, the less you have of the other. So, if we speak of a ‘secular intellectual’, we mean someone who expressly identifies as not belonging to any ‘religion’.  This is not like the Christian usage, where ‘religion’ and ‘the secular’ are supposed to be co-operating partners.

Why is this important?

For two reasons. The first is quite simple: when we read British sources from prior to the ‘secular revolution’ of the 1960s, we need to be sure we’re not misinterpreting them as employing the secular usage of ‘secular’ when actually they’re employing the Christian usage. This mistake will trick us into thinking that ‘secular’ people (in the secular usage) were much more numerous prior to the 1960s than they in fact were.

The other reason is quite fundamental: that the uses of these categories reflect the cultures that created them. These two usages of the terms ‘religion’ and ‘secular’ are quite distinct: they reflect different worldviews. This means that, as Britain’s Christian culture declined, there was no automatic or easy way for people to slip from the Christian usage into the secular usage. Instead, this transition took cultural work. Someone, or some people, needed actively to rework these Christian categories to create the secular usage. My research suggests that, for the mainstream of British public culture, this transition mostly took place in the late 1950s and early 1960s, thus enabling widespread and permanent ‘secularisation’ to become widely thinkable, as it hadn’t been previously.

So two crucial lessons are embedded into the very language of the secularization debate – lessons which subvert much of the way in which that debate has been so far been conducted. First: Britain’s shift from the Christian framework to the secular framework was a transformation, not an evolution. It required a distinct reworking of some fundamental categories. Second: this transformation required active human creativity. It was not an automatic process of history.