“The desire for God is written in the human heart because man has been created by God and for God,” the Catechism reminds us. How can we be sure that God exists?

The human person is inherently oriented towards God. “The desire for God is written in the human heart because man has been created by God and for God” (CCC, no. 27). Even if someone doesn’t overtly feel a desire for God, they may feel a desire to understand the meaning of their life, or to seek true happiness, or to be a good person, or to experience true love. And because God is ultimate Truth, Goodness, Love, and Beauty, all of these desires are signs that we were made to know and love God.

We can discover the existence of God through philosophical proofs. A philosophical proof is not ‘proof’ in a scientific sense (the belief that we can only know things through empirical, scientific data is a fallacy called “scientism”). A “proof” in this context is a compelling philosophical argument that is deduced from what we can see and touch in the world around us.

There are many philosophical proofs. William Lane Craig summarises four key proofs for the existence of God in his book Reasonable Faith:

1. The ontological argument

Here is a summary of the Ontological Argument:

• Nothing greater than God can be conceived of.
• It is greater for something to exist in reality than just in the mind (what’s greater: an orange or the idea of an orange?)
• If God did not exist in reality, then we would be able to conceive of something greater than God, i.e., a God who exists in reality.
• Therefore, God must exist in reality.

This argument was first defended by Saint Anselm in the 11th century. However, today, some people prefer not to use it, because it can sound more like clever rhetoric than a serious argument.

2. The cosmological arguments

The cosmological arguments are some of the most popular proofs for the existence of God. In a cosmological argument, we begin by looking around at the things that exist, and then argue backwards from those things to a first cause, or God. The most popular example is St Thomas Aquinas’ Five Ways. Here is a summary of his First Way, known as the argument from motion:

• Everything that exists is in a state of “motion”, or change.
• Every change that occurs is prompted by something external to that thing (e.g. a stone becomes sand because of the influence of wind, rain, and gravity). Nothing changes entirely of its own accord.
• If we zoom out, we can see existence as a seemingly endless system of changes. However, there must be something that started the whole system going, like a hand reaching out to set off a row of dominoes or to switch on a machine (for a visual analogy, check out this video by the band OK Go).
• That “hand” that started the whole system going has to be outside the system. If it were not, then it would be part of the system and would itself need something to set it off.
• Therefore, existence requires an “unmoved mover” – that is, something that does not itself change, and does not require anything else to set it in motion, because it is existence itself.

That something, we call God.

3. The argument from design

When we see how complex, beautiful, ordered, and finely tuned the universe is, it is natural to conclude that it must have been designed by an intelligent mind. Existence is too ordered to be random. Even something like Andy Goldsworthy’s simple artworks (check them out!) are too ordered to be random. If a few twigs can suggest the presence of an intelligent mind, how much more must our intricate world suggest one!

This argument is sometimes looked down on by people for not being philosophical or academic enough. But why should an argument be invalid simply because it is simple? God has left his fingerprints on nature, and it is perfectly valid to see those fingerprints and deduce that they belong to him.

The argument from morality

There are certain things that humans agree are right and wrong. We agree that it is right to do good and avoid evil. Of course, today many people consider themselves relativists. But even relativists believe that there are some things that are intrinsically wrong (like genocide, rape, or murder).

Objective morality matters. Accepting that there are some truths that are not socially constructed is the first step on the path to God, because it is an acknowledgment of the transcendent.

When we say that something is good or bad, we are placing that thing on a scale, at either end of which is Ultimate Good and Ultimate Evil. And Ultimate Good, goodness itself, is simply another word for God (more on this in a later episode!).

While philosophical proofs can show us that there is a God, we need to go further than that. God is not just a series of facts, but a being. Having an intellectual belief in the existence of a God is a good starting point, but we need to go further. We need to get to know this personal God who created us. And this is what we will explore in the next few episodes.

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Discussion questions:

• Which of the philosophical proofs of the existence of God do you find most compelling? How would you explain this proof to a friend who doubts that God exists?
• Which of the proofs do you find most challenging to accept? Why?
• How do you explain the idea that “everyone desires God on some level”?
• What are some examples of actions that are universally considered right or wrong, regardless of cultural or personal beliefs?
• When there are so many different points of view and ways of experiencing the world, how do you explain objective morality and why it matters? Why is it that someone who isn’t living an upright moral life will find it difficult to believe in God?

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More resources:

• The Catechism of the Catholic Church, Pts. 26-49
• The Catechism in a Year, “Day 5: How We Know God”
  • “Day 6: Knowing God with Certainty”

On arguments for the existence of God:

• William Lane Craig, Reasonable Faith (Book)
• William Lane Craig, Reasonable Faith (Website)
• Edward Feser. Five Proofs for the Existence of God, The Last Superstition, Aquinas.
• Peter Kreeft
  • “Twenty Arguments for God’s Existence”.
  • Letters to an Athiest
  • Handbook of Christian Apologetics
• Pints with Aquinas podcast:
  • 02: Do we need faith to know that God exists?
  • 17: Is the ontological argument for God’s existence sound?
  • 07: Who created God?
  • 30: Has science done away with the need for God? With Trent Horn
  • 19: Give me an argument for the existence of God?
  • 33: What’s the contingency argument for God’s existence?
  • 56: What are the 4 causes of Aristotle? How do they apply to your 5 ways?
  • 46: Can you explain your argument for God from design? With Dr Robert Delfino
  • Responding to Hank Green’s objections to Aquinas’ 5 ways
  • Why Ricky Gervais is wrong about God, knowledge, science, and religion, with Trent Horn
  • Can Philosophy Prove the Beginning of the Universe?
  • Ed Feser Responds to Richard Dawkins on Thomas’ 5 Ways
• Cameron Bertuzzi, Capturing Christianity Youtube channel.

On the argument from desire:

• Ted Chiang, “What’s Expected of us”, from Exhalation. (His other book, Stories of Your Life is also really worth reading – in my opinion it’s better than Exhalation.)
• C. S. Lewis, Surprised by Joy.
• St Thomas Aquinas
  • Summa Contra Gentiles III.48. Another permutation of it appears in II.55.
  • The Summa Theologiae 1.75.6
• The following quote from Kristin Lavransdatter, by Sigrid Undset:
  • “There is no one, Kristin, who does not love and fear God […] For if a man knew no yearning for God and God’s being, then he would thrive in Hell, and we alone would not understand that he had found his heart’s desire. Then the fire would not burn him if he did not long for coolness, and he would not feel the pain of the serpent’s bite if he did not long for peace.”

On the argument from motion:

• Ok Go, “This Too Shall Pass – Rube Goldberg Machine – Official video.” YouTube. https://www.youtube.com/watch?v=qybUFnY7Y8w

On the argument from design:

• Special Books by Special Kids (SBSK), Youtube channel.
• Thomas Riedelsheimer’s documentary, Andy Goldsworthy: Rivers and Tides.

On the argument from morality:

• C.S. Lewis, Mere Christianity.
• G.K. Chesterton, Orthodoxy.