Suppose you have a militant atheist friend who challenges you with the above statement. How do you respond?

To me, the only answer is to yield the point, but to dispute the assumption. Your friend is attacking you because they are assuming that the word ‘irrational’ implies ‘bad’ — that anything that cannot be rationally explained is, in itself, bad.

Yet this is in itself a case of generalizing too far, and our hypothetical challenger would have to agree that there are many non-rational things in the world which are fairly uncontroversially natural and good: emotion, for instance, is something which cannot be rationally grounded. Love for someone, perhaps the most deeply and thoroughly experienced emotion of all, cannot be explained by an experiment or a formula, or listed in a table. It cannot be ‘rationally’ explained — except as interactions between neurons and chemicals in the brain, which tells one almost nothing about the lived, inward human experience of love.

At the same time we would hate to have that lived human experience of love described as irrational: the word has too much baggage; it sounds derogatory. We like to think that there are two kinds of non-rationality — ‘good’ and ‘bad’. Bad non-rationality, or irrationality, is the result of not thinking hard enough about what you’re doing — it is prior to and can inhibit rational thought. Faith can be irrational; anything, I would hazard, which can be a form of ‘good’ non-rationality can also be irrational. It is possible to be led astray by one’s emotions — not just by love, but also by fear, depression, or even hope or joy — into doing things which are quite obviously bad ideas; likewise, even someone whose faith is ordinarily quite healthy for them can, at times, be led by it to do wrong things.

If irrationality is what blocks us from doing rational things, the kind of non-rationality form which faith should spring is the same kind as love, which comes after rationality. After we have thought about it, we consent to let it consume us.

Our hypothetical friend might then reasonably object that emotion is quite different from religious faith (at least the religious faith of a Christian, or of faiths like it): religious faith, unlike emotion, they might claim, is not only a purely inward experience but involves making claims of factual truth about the outside world. Christianity tries to tell us about the origin, purpose, and ultimate fate of humanity and of the entire world; and whereas emotion does not need to be proven, these claims still surely do.

I admit I cannot answer this rebuttal in a way that would be likely to satisfy the questioner. All I can counter is that just as my challenger finds love an inwardly meaningful experience, so I too find Christian faith inwardly meaningful, and that the factual claims of Christianity are not really claims in remotely the same sense as scientific theories: increasing scientific knowledge ought to increase our wonder at the mystery and richness of God’s creation, not cause us to cast doubts on our faith. That much applies as equally to the mystery of the creation itself, as to the relevations of God through the patriarchs and prophets and the divine ministry of Jesus.

A ‘God of the gaps’ who existed in gaps large enough for naïve interpretations of Christianity’s factual claims had already been squeezed out of the gaps by the 17th century. The French mathematician Blaise Pascal wrote scathingly of attempts to rationalize God into the then-new scientific method in his Pensées : ‘It is the heart which experiences God, and not the reason. This, then, is faith: God felt by the heart, not by the reason.’

In a quote commonly attributed to him he was especially dismissive of Descartes’s perceived deism, feeling that a God who seemingly had nothing to say would not be worth having anything said about him; yet more strikingly, in a note which he had sewn into his clothing, Pascal writes of being overcome by religious feeling one evening, and writes almost in the manner of a modernist poet, and it is clear that this evening affected him profoundly. I take much comfort from the fact that Pascal — one of the 17th century’s leading scientists — was able to so completely submit to his faith to have this experience.

The year of grace 1654.

Monday, 23 November, feast of Saint Clement, Pope and Martyr, and of others in the Martyrology.

Eve of Saint Chrysogonus, Martyr and others.

From about half past ten in the evening until half past midnight. Fire ‘God of Abraham, God of Isaac, God of Jacob,’ not of philosophers and scholars.

Certainty, certainty, heartfelt, joy, peace.

God of Jesus Christ.

God of Jesus Christ.

My God and your God.

‘Thy God shall be my God.’

The world forgotten, and everything except God.

He can only be found by the ways taught in the Gospels.

Greatness of human soul.

‘O righteous Father, the world had not known thee, but I have known thee.’

Joy, joy, joy, tears of joy.

I have cut myself off from him.

They have forsaken me, the fountain of living waters.

‘My God wilt thou forsake me?’

Let me not be cut off from him for ever!

‘And this is eternal life eternal, that they might know thee, the only true God, and Jesus Christ whom thou hast sent.’

Jesus Christ.

Jesus Christ.

I have cut myself off from him, shunned him, denied him, crucified him.

Let me never be cut off from him!

He can only be kept by the ways taught in the Gospel.

Sweet and total renunciation.

Total submission to Jesus Christ and my director.

Everlasting joy in return for one day’s effort on earth.

I will not forget thy word. Amen.

Thanks to Megan Kramer for a key insight in the development of this essay.