Probably the most well-known intellectual atheists of the 20th century were Albert Camus and Jean-Paul Sartre. However Camus privately and Sartre publicly converted vaguely to monotheism, Catholic and Jewish respectively.

A look at the rationale behind their conversions constitutes the best case for the existence of God. We may call this the existentialist argument for God. It’s also touched by Pascal, Kierkegaard, Chesterton, Lewis, Wittgenstein, and the film (I haven’t read the book) Life of Pi.

First, ground rules:

1. God’s existence or non-existence cannot be objectively demonstrated through empirical evidence or deductive argument. Why?
2. Because the question of God, by most definitions, concerns basic presuppositions about reality itself. Contra “new atheism” the question is not scientific. It is pre-scientific, pre-theoretic, as Karl Popper eloquently stated. Consider:                      
3. You can demonstrate the proposition “a tree exists” by showing a tree to me. You and I share (in language and practice if not in conscious theory) basic presuppositions like the physical world exists, other minds exist, and one can satisfactorily demonstrate to other people that a tree-size physical object exists by showing it to them.
4. But you cannot objectively demonstrate basic presuppositions themselves. We have no common ground here, no criteria for satisfactory objective demonstration in language and practice..

So how could we move forward? Is the question itself pointless, leaving us only the agnostic or the arbitrary? Not necessarily. (Not if you care about the question anyway.)

Wittgenstein in Culture and Value (1984) offers the imagery of iron. Physical sciences, deduction, and so forth are cold. You need cold to set the molecular bonds and use the tool. But first you need heat. As heat forges iron, so intuition and reflection and personal experience mould our understanding of the scaffolding of reality. These are other, more fundamental, more necessary means of knowing than objective empiricism. These are the kind of methods you must use if you are to investigate the question of God.

Which basic presupposition—atheism or theism—makes more sense of your experience of the universe? There is no objectively right or wrong answer here.

The universe that we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, no good, nothing but pitiless indifference.

—Richard Dawkins

As for me, I don’t see myself as so much dust that has appeared in the world but as a being that was expected, prefigured, called forth. In short, as a being that could, it seems, come only from a creator; and this idea of a hand that that created me refers me back to God.

—Jean-Paul Sartre

Does the possibility and actuality of a physical universe ordered by natural laws make more sense to you under the lights of atheistic or theistic presuppositions? Does the possibility and actuality of meaning or purpose in human experience line up better with one or the other? Paraphrasing Life of Pi, “given you can’t objectively determine which story is true and given the immediate result is the same, which is the better story: the one with the cannibalism or the one with the tiger?”

For me, the most interesting observation is that in fact humans have this wide sense of purposeful personhood which may make more sense under the theistic premise of a transcendently purposeful personhood in God.

I don’t know whether I’m convinced. I remain agnostic for the time being. The iron’s still hot.

Pulse

This is not how hearts begin
to beat, in twos
sitting in trees. Soaked birds say
we’re cold, and go inside.
No one around us has a problem
breathing. Whole branches
collapse under the weight of ice
and skin. Nations cave
in the time it takes a heart to stop
beating. And what of surrender?