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What is religion for? Philosophy versus Theology

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Dr Han van Ruler is Professor of Intellectual History and Vice-Dean of the Erasmus School of Philosophy, at Erasmus University Rotterdam. Through his research, which focuses on Erasmus, Descartes, Geulincx, Spinoza, and Leibniz, he explores the development of theology and its move towards philosophy. Dr van Ruler examines how early modern thinkers were able to effectively combine the Christian command to wait until death to experience pure joy with moral philosophy, which argues for human progress towards ecstasy in this life.

The purpose of religion has been debated throughout history with a particularly significant shift occurring in the early modern period, in the sixteenth and seventeenth centuries. In some ways, this was a golden period of philosophy. However, new and emerging ideas on human perfectibility and the separation between mind and body threatened established religious orthodoxy. Dr van Ruler’s work examines these conflicts and presents Spinoza’s philosophy as the ultimate attempt to arrive at a solution.

Thomas More versus Erasmian ecstasy

In his essay, Beatitude and the Scope of Grace, Dr van Ruler explores the conflict and the contrast between what God expects of his followers and what philosophers expect with a view to moral progress and social cohesion. This debate centres around a verse from 1 Corinthians 2:9, in which Paul says, ‘Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him’. In the sixteenth and seventeenth centuries, there is no doubt that this refers to the most indescribable ecstasy. But does it only pertain to ecstasy for the mind after death?

For Thomas More, this verse is merely about life in Heaven. He does not consider the Bible to give much advice on how to live here and now on Planet Earth. Instead, Paul’s writing is interpreted to be about waiting for God to provide true ecstasy. Until then, there is no need to think about fleeting, earthly pleasures.

More’s interpretation of the scripture is the opposite of that of Erasmus and many later early-moderns. They are keener to promote the idea that these joys can be experienced in the present. God, according to the Erasmian view of ecstasy, is ready to provide His followers with bliss in this life and moral philosophy should be used to facilitate this.

“Early modern philosophers dip their toes into moral philosophy, particularly the idea that we can improve our lives in the physical world, rather than waiting for God in the Afterlife.”

The mind’s potential for boundless joy

At this point, Dr van Ruler opts to bring Cartesian dualism into the discussion, a philosophical position that was developed by Descartes in the early modern period. Philosophers such as Geulincx and Spinoza agree with Descartes that there is a strict separation between the flesh and the spirit. They assert that the mind, being unbounded, is capable of experiencing limitless joys. Meanwhile, there is no limit to the pain that can be felt in the body. You may be burnt or hurled face-first onto a stone floor.

‘Interior with a Mother close to a Cradle’ (c. 1663), a painting by Dutch painter Pieter de Hooch, serves as an illustration of Geulincx’ argument that the baby in a cradle is like a human being in God’s hands: it wishes to be rocked and is indeed rocked, but only by the power of the mother who rocks it.

Although many reject Stoic philosophy, they accept the premise that the body is being continually tossed around in a ‘boundless ocean of miseries’. We have no control over our fate and are enslaved to our passions. To overcome this, early modern philosophers dip their toes into moral philosophy, particularly the idea that we can improve our lives here, in the physical world, rather than waiting for God in the Afterlife.

This led to Christians increasingly embracing a Stoic view of ataraxía and an Aristotelian notion of felicity. Both terms relate to a state of physical and mental happiness that can be arrived at through moral progress. Spinoza, building on the ideas of Erasmus, concurs with Geulincx in believing that ecstasy and boundless joy come through the ‘love of God’ but from an intellectual, philosophical perspective.

Blurring natural ethics and religious dogma
At the same time, Spinoza, despite his atheistic tendencies, could not help but see moral philosophy through the Christian lens of salvation. He thereby combined two lines of reasoning that gave conflicting interpretations to the unbounded joy written about by Paul.

The tension was apparent in both Catholic and Protestant sources. Dr van Ruler explores this through two examples. First, there is the Italian philosopher Piccolomini’s example, in which the problem of how to arrive at the ‘supreme good of man’ is simply taken to be either a religious question related to the afterlife or a question for ethicists, when applied to the things to be pursued in this life.

Engraving of Spinoza, captioned in Latin,
“A Jew and an atheist”.

Second, there is the example of de Wael, who, like Piccolomini, admires Plato. He believes that Plato has ascended higher than Aristotle by realising that the good of man exists only in the vision of God and not here on Earth. At the same time, there is ‘the other good’ – the natural and civic kind that Aristotle talked about. Trying not to blur the lines between natural ethics and religious dogma, there seemed to be no room for a unified philosophical and theological account of human felicity.

Aristotle’s Nicomachean Ethics is concerned with humans carrying out their civic duty. That means making society on Earth better rather than waiting around for heavenly rewards. This is dangerous to Christianity because it points to humans as being free, self-reliant, and autonomous. It also moves the debate from occurring solely between Christians and pagans to a broader debate concerning the extent to which the religious should accept the idea of a moral philosophy of man.

Dealing with dilemmas

The example of de Wael is, according to Dr van Ruler, inspired by Arminianism. This is because Arminianism, too, tries to reconcile the same conflict. On the one hand, there are Erasmian Christians who want to take a Stoic approach to life, mastering oneself in the worship of God. On the other hand, there are Christians who do not believe in moral progress but would rather suffer in this life, relying on the redemption of Christ to bring them eternal joy after death.

Portrait of Desiderius Erasmus by Albrecht Dürer, 1526, engraved in

In the mid-seventeenth century, Geulincx takes the former view. He argues that moral truth must first be revealed in scripture by God. From here, though, it is possible to achieve moral and societal progress using pure reason, without the help of a transcendent being. Geulincx claims that this is the reason why pagans are never able to find joy on Earth: they have not read and understood the scripture, so they cannot progress with their moral reasoning. Despite using the work of Plato, Aristotle, and the Stoics, Geulincx contends that these pagans are bound to fail.

The dilemma with this view is that it argues that happiness is achieved through the fulfilment of duty. However, the duty must be carried out without happiness as an aim. Geulincx promotes finding the right laws to ensure that people receive God’s love for the correct reasons.

Spinoza’s solution

Geulincx leaves us with a theological riddle: how can we be sure that our love for God is not merely offered out of our own selfish desire for joy? It is Spinoza who formulates an answer to this riddle. He does this by combining the concepts of divine grace with a consistent and reasonable moral philosophy. He accepts that philosophy and religion share a common goal: to make better humans.

What form does salvation take? Can everybody go to Heaven? Jorm S/

In addition, redemption also becomes a philosophical topic in Spinoza. Man can be redeemed by metaphysical necessitarianism, rather than relying on religious revelation. This is a Stoic viewpoint that explains beatitude is offered by God to those who follow reason, but also that the recipient must accept that they have no control over it. Again, this is a Stoic conception of fate.

Spinoza’s claim is that we must surrender completely to the divine. This amor Dei – the love of God – redeems man. Spinoza, though, is no Christian. His conception of God refers to Nature. Nevertheless, the point is to find salvation through living a good life.

“Capéran believes that salvation must be fair and open to all.”

Moral and existential forms of salvation

The question, then, concerns the form which salvation takes. For Thomas More, it is a personal, introspective consideration. For Erasmus, religion should be seen through the lens of social duty and moral progress. But what is the fate of the pagans? How can Christians account for their salvation? At this point, Dr van Ruler leaves the early modern period behind and jumps to the ideas of Louis Capéran.
Capéran favours the Catholic approach, which leaves room for the salvation of pagans. He is, conversely, fiercely critical of Protestants who were happy to allow access to Heaven only for a small elite of devout believers. Capéran considers this view to be arbitrary and unjust, something that goes against the idea of God.

It turns out, though, that in making this religious case, Capéran is taking a philosophical position. He lands, as many philosophers do, on the side of fairness. He believes that salvation must be open to all. His opponents, relying on theology, argue that salvation must be overwhelming and outside of human control and, therefore, cannot be entirely fair and inclusive. Capéran’s propensity for fairness, it seems, began with the discussions in the early modern period, outlined above.


The great leaps made by moral philosophy in the early modern period had profound and lasting effects on theology. It laid the groundwork for lawmakers and citizens to work together on creating joy in this life, rather than merely waiting for the afterlife. Yet to provide a link between earthly felicity and the beatitude of salvation, theology and philosophy needed to converge and develop into a single system of thought. Paradoxical as it may seem to believers and atheist alike, it was only Spinoza who succeeded in giving an interpretation to human felicity that was at once social and redeeming, practical and personal, moral and religious. This prototypically ‘modernist’ viewpoint was in fact the naturalised version of a religious position.

What inspired you to conduct this research?

Originally trained in seventeenth-century natural philosophy, I was struck by the moral twist some of Descartes’ followers gave to Cartesian philosophy, Geulincx and Spinoza in particular. Studying the background to their views, I realised that moral philosophy in early-modern times is by and large still an unexplored field – even a blind spot in Western philosophy’s self-image. Studying our moral past helps us understand the multifaceted historical background to present-day cultural mentalities, not only in relation to philosophy and theology, but also, for instance, with respect to what we have come to understand by ‘freedom’ – which is one of my current interests.

Why must salvation be fair?

I see no reason to make demands on either God or reality, but I do see a tension in religious systems between moral aims and motivational means. In Christianity, part of what drives people is fairness. The urge to imitate Christ is, of course, very powerful in this respect. Historically, however, it is a theme that loses out in the fight for dominance with other themes, especially the idea of being ‘saved’ by Christ no matter what. Religious dogma is often about what takes place behind the scenes, in the world of the divine. This is also what primarily triggers religious feelings. One of the reasons why the more orthodox parties were often also the more popular in early-modern Europe is that people are psychologically motivated rather more by the idea of being saved than by the idea of doing good.



  • Van Ruler, H. (2006). ‘Introduction’, in Geulincx, A. Ethics. pp xv-xli.
  • Van Ruler, H. (2009). ‘The Philosophia Christi, its Echoes and its Repercussions on Virtue and Nobility’, in MacDonald, A. et al. (eds), Christian Humanism: Essays in Honour. pp 235-263.
  • Van Ruler, H. (2020). ‘Beatitude and the Scope of Grace: Early Modern Morals and the Paradoxes of Felicity’, in Frigo, A. (ed). Inexcusable: Salvation and the Virtues of the Pagans in the Early Modern Period. pp 107-123.
  • Van Ruler, H. (2020). Of Dogs and Men: The psychological and the ethical in Descartes and Spinoza. Rivista di Filosofia Neo-Scolastica. 112(2). pp 393-410.

Research Objectives

Besides his work on 17th century natural philosophy, science and metaphysics, Dr Han van Ruler examines the early modern debate between Christians and moral philosophers, with particular recourse to the thinking of Spinoza.


Netherlands Organisation for Scientific Research NWO


Han van Ruler is Professor of Intellectual History and Vice-Dean of Erasmus School of Philosophy (Erasmus University Rotterdam). He is General Editor of Brill’s Studies in Intellectual History, the author of numerous works on early modern thought and (co-)editor of modern editions of works by Descartes, Geulincx, Spinoza, and Leibniz.

Han van Ruler


twitter: @hanvanr

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