The Netherlands is not usually considered as having an exciting politics. Nor is it regarded as a stronghold of religious conservatism at least in recent centuries. But the Netherlands in the early 20th century was all these things and more it was divided by deep political cleavages- cleavages as deep and vicious as the cleavages that divided Conservative and Labour in the 1980's. Indeed I would argue they were fundamentally greater. For they were not simply differences in polic and voting (though they were that) but differences in people's entire mode of existence.
The First of these cleavages was class –like just about every European country. By World War 1 there was a vigorous Labour party in Holland. it mobilized workers and others ( some of the earliest gains were among poor fishermen in the North of Holland) behind such issues as an expanded welfare , legal rights and protections for trade union . AT the same time the power of working class was not confined to the Labour party- the religious parties had many working class voters and many voters’ sympathetic to at least some of labor’s leftwing economic agenda (this was particularly true of Catholics). Vicious strike battles were routine in early 20th century Holland and the entire country was divided on the basis of Class. Examples of the policy issues fought on class lines and identify were the laws affecting unions.
The second was arguably more important and was that between the secular (including many praticising liberal Christians) and the pious) and the pious. IN many ways modern Dutch politics was born in the late 19th century in the fight over the attempts to secularize the schools .This caused an alliance of disparate Christian religious and political traditions to oppose-this a fight they essentially won by the early 20th century but the battle over the degree of secularism in the public sphere and the degree of latitude and influence for orthodox/ "conservative" religous very much remained. An example of issues were such issues were important were divorce and schooling. The secularism and even atheist Marxism of the early Dutch Labour Party (very unlike the British of the era) was enormously alienating to the Catholic Church .. As late as the 1950's the Catholic Church excommunicated people for subscribing to the Dutch labour party's newspaper!
The third was the Catholic Protestant division in many ways the most profound of all and certainly the oldest. Importantly was in nearly all cases a very clear division while class divisions and secularism were more matters of degree and thus the separation of matters of life like church attendance or marriage practices was sharper for sectarian divides than the other. Two other aspects of the Catholic Protestant division were very important. Firstly the two groups were very geographically divided the south (whcih had been under ardently Catholic Hapsburg rule longer) was overwhelmingly catholic the north and center of the state Protestant. Secondly the default mode of Dutch politics and society was Protestant (though often not the majority of churchgoers) , the majority of the public identified as such, the monarchy was Protestant and so forth. This meant the huge number of secularist politicians (even atheist) were effectively Protestant secularists. An example of issues where Catholic Protestant divides were important was the right of Catholic religious processions to March in public and the recognition of the Vatican (a massive issue in 1920's Dutch politics)
The Fourth was between the Protestant state Church and the breakaway Reformed Churches of the Netherlands. The division was ultimately about whether a denomination could include “heretical” protestant Christians for example those who denied biblical miracles. The latter left the former over this issues. It should be noted the state church included many who were strongly conservative in personal faith and even many who wished to exclude liberals-but did not wish to leave their denomination over the issues preferring to work from within. In a sense this social cleavage was between separatist and anti-separatist christians. No single political issue necessarily correlated with these divisions but one important one was to be the theology and politics of "sphere Sovereignty" which sought a third way between governments imposed secularism and government imposed theocracy supported by many establishment Christians.
All these cleavages helped shape the "pillars" of Dutch society. All were linked to sharp political divisions but it is important to realize that they went well beyond that- even people not at all interested in politics were intimately affected by them. They affected how they worshipped, which schools they went to , which newspapers they reads who they married in short nearly all aspects of everyday life. This led to parties much more deeply rooted and distinct than in just about any Anglo-Saxon Democracy.