Go into any large bookstore and you’ll find a section labelled something like “Body, Mind and Spirit”. Browse the books and you will find a bewildering array of beliefs represented, some rooted in scientific research, but many in the world’s various religions. What, then, does the Christian Bible have to say about the subject?

The New Testament was written in Greek, and it uses some key words which have found their way into English. The word spirit – whether that refers to the Holy Spirit, who is God, or the human spirit within each of us – is pneuma, literally meaning ‘breath’, from which we get pneumatic (air-filled) tyres. Our English word spirit has come through Latin, where we see the presence of breath seeping into words like respiration.

Two Greek words are used to refer to our bodies. The more general word is soma (biologists speak of ‘somatic cells’ to mean cells in our bodies which are not part of our reproductive line). A more specific word is sarx, literally “flesh”, which is usually chosen when the Bible wants to dwell on negative aspects of our bodily existence (think of ‘pleasures of the flesh’). The word found its way into English for sarcasm, which literally means “flesh-cutting”!

There are also two words which can be used to indicate our ‘mind’, our place of thinking. The Greek New Testament often uses the word psyche – which gives us many English words including psychology and psychiatry – and this must be translated carefully. Should it be rendered “mind” or “soul” – and might the Greek word in fact express different shades of meaning in different Bible texts?

In I Thessalonians 5, St Paul prays that God will preserve “spirit, soul and body” – pneuma, psyche and soma. Article 367 of the Catechism of the Catholic Church notes this apparent distinction of soul and spirit, warning that this “does not introduce a duality into the soul”. Generally English translations of Scripture render psyche as “soul”, as in Mark 12 (alongside the use of “mind” to translate dianoia). 

Many books by evangelical Christians take I Thessalonians 5 as a guide to speak definitively of human beings as a three-part reality: body, soul/mind, and spirit. The Catholic Church is more cautious but each of these words does have something to teach us. We might find it helpful to use language developed by the Chinese Christian, Watchman Nee, where the spirit is the “Inner Self”, the mind is the “Outer Self” and the body is the “Outermost Self.” 

Scripture explicitly speaks of the Inner Self: it delights in God’s Law (Romans 7), is renewed while the outer is consumed (II Corinthians 4) and is strengthened by God’s Spirit (Ephesians 3). Baptism regenerates the Inner Self, because the Holy Spirit comes to dwell there (I Corinthians 6). Our Outer Self is the locus of thought, emotion and will; in John 12, Jesus teaches we must lose our Outer Self in order to keep it eternally.  

There is another quite distinct way to use the word ‘soul’, and this may be more helpful to our Catholic understanding. Rather than referring to our ‘Outer Self’, soul (psyche) could indicate our Whole Self. We are used to speaking of the “Holy Souls”, deceased persons whose spirits have left their bodies and are presumed on the path to heaven, undergoing a final purification assisted by our prayers. (We might see a hint of the Catholic doctrine of Purgatory for such souls in the passages where Jesus warns sinners not of eternal damnation but of a place of punishment; a prison they cannot leave until they have paid the last penny: Matthew 5 & 18, Luke 12.) We do sometimes use the word ‘soul’ to mean the ‘whole person’, such as when a report notes that a ‘ship capsized with 20 souls on board’.

Right now, my soul (my Whole Self) consists of a body (soma) of flesh (sarx) inhabited by a spirit (penuma). When I draw my last breath, my spirit will exit my body and most likely join the Holy Souls (in their spirit-only state) on the way to heaven… or my spirit could go directly to heaven or, if I have turned away from God’s mercy to hell. 

In the Creed recited at Sunday Mass, we profess the resurrection of the body – this is not referring to Christ’s Rising, but to how we ourselves will be given Body 2.0 at the Last Judgment. Scripture does not give us many details about what awaits us, but that we shall have renewed and everlasting bodies is made clear in Luke 14, John 5 and I Corinthians 15, as well as the Book of Revelation.

If our brains truly were nothing more than computers made of meat, then a proven principle of computer science (the Turing machine theorem) is that software which runs on one computer can be made to run on any computer. At the Resurrection, God – who knows all – can surely reproduce the software from my defunct Brain 1.0 to run in Body 2.0. But Scripture points me in the direction of believing that I do have a spirit, which will be capable of surviving the demise of my flesh in a disembodied form.

Modern science would question the idea that we have a ‘spirit’ at all, taking the default position that our mind, our consciousness, is most likely generated by the ‘software’ running in the complex processor which is our brain. If we do indeed have a ‘spirit’ it must be mediated in some way by our brains, since brain damage can severely limit the self-expression or free action of a person.

We now have scanners which allow us to watch the processes in living human brains, and the field of neurophysiology is rapidly developing our understanding of how brains actually work. We have nothing to fear from this; the Catholic Church acknowledges that it is right and proper for science to use its own methods to advance human understanding. But the scientific study of human thought leads us into two controversial areas: consciousness, and free will.

What exactly do we mean by consciousness? Is it more than self-awareness? As we explore the animal world around us, we have discovered that crows can solve complex problems to access food; parrots and dolphins seem to be able to use sounds which are distinct ‘names’ for other individuals in their own species; and that whales communicate with complex songs which shape their social behaviour. From a purely biological view, human beings happen to be the species which first evolved the richest culture and use of language; there is no reason other species could not do so, given time. From a Biblical point of view, our uniqueness is not just a matter of degree but of substance; humans alone are ‘very good’ and ‘made in the image of God’ (Genesis 1). Our Biblical stance might make us prize human consciousness as our Godlike ability to reason, love and communicate. Scientists are more cautious and ask: “What do we mean by consciousness?” and have not yet reached a consensus.

The Bible also makes clear that God will judge human beings on the basis of the decisions we make in life: Jesus tells the famous parable of the sheep and goats in Matthew 25, while St Paul (Romans 2) expects that those who did not know Christ will be judged on how well they heeded their consciences. But if I am to be judged, surely this implies that “I” am in control of my decisions?

If my brain were merely a computer, it would either follow classical physics or quantum physics. In classical physics, we always get the same output if we program a system with the same input – this leaves no room for ‘free will’. In quantum physics, the state of a system is inherently random and not settled until someone makes a ’measurement’. 

The question of what counts as a ‘measurement’, and whether conscious observers are required to bootstrap the Universe into existence, are hotly debated in modern physics, with no settled view. I lean in the direction of believing that it is my spirit which somehow (quantum or otherwise) allows me to meaningfully exercise free will in making my decisions, and on that basis my spirit will be rightly judged by God. It would surely be unfair for me to be judged on decisions which were either 100% predetermined or totally random. As for whether brains mediate an intangible spirit, or whether there is a fundamental connection between ‘consciousness’ and quantum physics? These are mysteries for which only time will tell if science can provide an answer. 

Revd Dr Gareth Leyshon is a parish priest in the South Wales Valleys, who read physics at Oxford and completed a doctorate at Cardiff (a study of the structure of distant galaxies) before entering seminary.

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