Back in the early 80's, I spend many an afternoon in a cramped and stuffy office in King's College, London, with an informally gathered group of mostly graduate students, going through Wittgenstein's Philosophical Investigations paragraph by paragraph, line by line. It was often terribly slow going. We might ponder two or three sentences for a couple of weeks, coming back to the same point several times. It felt a bit like Bible study. Some might have wondered how much was being achieved in this group or what the point of it all was. But for me it was absorbing, thrilling, adventurous. My eyes were opened and my life was changed.

The professor at the centre of this little group was the genial Texan philosopher Norman Malcolm, a lifelong friend of Wittgenstein and one of his most notable students. Part of the excitement – though nobody would have been quite so crass as to admit it – was to be learning philosophy at just one degree of separation from the master himself. But that alone was not what made this group keen to keep coming back. Many of us felt that something different was going on, that we were learning a new way of doing philosophy. The big idea was that philosophy wasn't so much a question of mastering arguments – though the they did form a small part. There wasn't any great sense that we were deriving firm conclusions from the logical combination of indubitable premises. Rather it was as if we were being inducted into a certain sort of technique, almost a style of dealing with philosophical problems. Philosophy was more like therapy, an attempt to understand and deal with the very heart of human puzzlement about various things. Why, we asked, do certain sorts of situations or ideas seem odd to us and what do we hope to achieve by throwing philosophy at them?

Famously, Wittgenstein had two phases in his philosophical development. He published the Tractatus Logico-Philosophicus in 1922. He then gave up philosophy to become, variously, a schoolteacher and a gardener and an architect. But after a break from professional philosophy he increasingly he came to see that there was something fundamentally wrong with his first book – not just that the arguments were mistaken, but that the whole way of doing philosophy represented by the Tractatus was completely wrongheaded.

In this second phase, Wittgenstein came to argue that the basic form of a philosophical problem was the inability properly to orientate oneself within a particular world of language. To anticipate: we get into philosophical muddles because language misleads us in to thinking the world is a certain sort of way. We get out of philosophical muddles by recognising how language really works, and specifically, that language is necessarily indexed to human practice, culture and behaviour – to what we do. "In the beginning is the deed" – a phrase that Wittgenstein as fond of quoting from Goethe. This series on Wittgenstein will attempt to expand on these points and try and explain how they constitute a new turn in the philosophical imagination.

So how does all this effect the God question? Well it doesn't and it does. In one sense, Wittgenstein's later thought makes great play of the insistence that it leaves everything as it is. That it is not the job of a philosopher to enter into questions about God and decide the matter. The philosopher is not the master adjudicator. But on the other hand, Wittgenstein can be said to dissolve certain sorts of anxieties about a religious worldview and steer a path away from the supposition that a religious person needs first to get the philosophical underpinning of his faith right before he or she can get on and practice that particular faith. For Wittgenstein, it is the practice of something that is properly foundational, not the arguments of the philosophers.

Soon after I finished with Norman Malcolm's group, I gave up any thought of doing philosophy permanently and joined the church. I had discovered the excitement of Christianity quite by surprise, by reading Kierkegaard as an atheist philosophy undergraduate. I found the music and liturgy of the church beautiful and profoundly moving. And as a disappointed ex-Marxist, I still wanted to change the world. But I could not give myself over to belief: too many philosophical problems blocked my path, too many questions about what sort of ontological commitment was being made by claims to God's existence. In Wittgenstein, I discovered a voice that advised me not to be endlessly detained these questions. In the beginning was the deed. One day I got up from my desk in the library at Kings and went out in search of the chaplain. We had never met. I didn't go to church. "How do I become a priest", I asked?