Arguments for God

What you'll learn

State and defend the Kalam cosmological argument and the Leibnizian contingency argument.
Explain the fine-tuning and moral arguments with concrete examples.
Compare how classical and presuppositional apologists use these arguments and show how they can fit together.

Why study theistic arguments?

Scripture says “the heavens declare the glory of God” (Ps 19:1) and that God's invisible attributes are seen in creation (Rom 1:20). Theistic arguments are attempts to put that testimony into clear steps; this is often called natural theology, reasoning about God from the world he made. Many sceptics have never heard them stated carefully, and many Christians are strengthened to learn that belief in God is intellectually serious.

First, some tools. In apologetics an argument is not a quarrel but a set of premises leading to a conclusion; a syllogism is a short one, usually two premises and a conclusion. An argument is valid if the conclusion follows from the premises, and sound if it is valid and the premises are true. Every argument here is valid, so to reject the conclusion a person must reject a premise. Since some premises rest on strong evidence rather than mathematical proof, the honest claim is that each is more reasonable than its denial.

Each argument has a simple logical form. Learn the premises by heart; most objections attack one specific premise, and knowing which one helps you stay calm and focused.

Why are theistic arguments worth studying, and why does the section advise learning the premises by heart?Show answer

Scripture says creation declares God's glory and makes his invisible attributes seen (Ps 19:1; Rom 1:20), and theistic arguments put that testimony into clear steps. Many sceptics have never heard them stated carefully, and Christians are strengthened to see that belief in God is intellectually serious. Since most objections attack one specific premise, knowing the premises helps you identify which one is under attack and stay calm and focused.

creation testifies to God
clear steps
strengthens believers
objections target a premise

What is the difference between a valid argument and a sound one, and why does it matter when someone rejects a theistic argument?Show answer

An argument is valid if its conclusion really follows from its premises, and sound if it is valid and its premises are also true. The arguments in this lesson are valid, so a person who wants to reject the conclusion has to reject one of the premises. That lets you focus the conversation on the premise he actually doubts, and the honest claim is that each premise is more reasonable than its denial.

valid: conclusion follows
sound: valid with true premises
to reject the conclusion, reject a premise
each premise more reasonable than its denial

The Kalam cosmological argument

This argument has roots in the medieval Islamic kalam tradition, notably the theologian al-Ghazali, and William Lane Craig revived it for modern debates. Its form is simple: (1) whatever begins to exist has a cause; (2) the universe began to exist; (3) therefore, the universe has a cause.

Premise 1 is a basic intuition: things do not pop into being from nothing. If they could, why do we never see it, and why only universes and not bicycles? Premise 2 is supported philosophically (an actually infinite series of past events seems impossible to traverse; you could never arrive at today) and scientifically (Big Bang cosmology, the second law of thermodynamics, and the Borde-Guth-Vilenkin theorem of 2003, which argues that any universe that has on average been expanding cannot be infinite in the past).

To unpack those supports: if the past had no beginning, an infinite number of days would have had to pass before today could arrive, like counting down from minus infinity to zero; you would never get there. And the second law of thermodynamics says usable energy runs down, so an infinitely old universe should already have gone cold. Be modest: cosmology changes, and Christians do not stake their faith on any one model. But the best evidence we have fits a beginning, as Genesis 1:1 says.

What kind of cause? A cause of all space, time and matter must itself be spaceless, timeless, immaterial and enormously powerful. Craig argues it must also be personal, because only a free agent can produce a temporal effect from a timeless state. That sounds a lot like Genesis 1:1.

State the Kalam argument in three steps and explain one reason given for each premise.Show answer

The Kalam says (1) whatever begins to exist has a cause, (2) the universe began to exist, so (3) the universe has a cause. Premise 1 is a basic intuition: things do not pop into being from nothing, otherwise we would expect bicycles to do it too. Premise 2 is supported philosophically, because an actually infinite series of past events could never be traversed to reach today, and scientifically by Big Bang cosmology, the second law of thermodynamics and the Borde-Guth-Vilenkin theorem.

three-step form
nothing pops into being
infinite past can't be traversed
Big Bang, thermodynamics, BGV

What kind of cause does the Kalam point to, and why does Craig say it must be personal?Show answer

A cause of all space, time and matter must itself be spaceless, timeless, immaterial and enormously powerful. Craig argues it must also be personal, because only a free agent can produce a temporal effect from a timeless state. That description sounds very much like Genesis 1:1.

spaceless, timeless, immaterial, powerful
personal: free agent
temporal effect from timeless state
Genesis 1:1

Explain in simple terms why an infinite past seems impossible and how the second law of thermodynamics points to a beginning.Show answer

If the past had no beginning, an infinite number of days would have had to pass one by one before today arrived, which is like counting down from minus infinity to zero; you would never arrive. The second law of thermodynamics says usable energy runs down, so an infinitely old universe should already have run down. We should be modest because cosmology changes, but the best evidence fits a beginning, as Genesis 1:1 says.

counting from minus infinity
usable energy runs down
infinitely old universe would have run down
modest: best evidence fits a beginning

The contingency argument

Gottfried Wilhelm Leibniz (1646-1716) asked, “Why is there something rather than nothing?” His argument uses the principle of sufficient reason: everything that exists has an explanation of its existence, either in the necessity of its own nature or in an external cause. A contingent thing is one that could have failed to exist (you, me, stars). A necessary being is one that cannot fail to exist.

The universe is a collection of contingent things, so it needs an explanation outside itself. An endless chain of contingent explanations never answers why the whole chain exists. So there must be a necessary being, existing by its own nature, that explains everything else. Unlike the Kalam, this argument works even if the universe were infinitely old. It points to a God who is “from everlasting to everlasting” (Ps 90:2) and who “upholds the universe by the word of his power” (Heb 1:3).

What is the difference between a contingent thing and a necessary being, and why does the contingency argument still work even if the universe were infinitely old?Show answer

A contingent thing could have failed to exist, like you, me or a star, while a necessary being cannot fail to exist. The argument says the universe is a collection of contingent things and so needs an explanation outside itself; an endless chain of contingent explanations never explains why the whole chain exists. Because it asks why anything exists at all rather than when it began, it works even if the universe had no beginning.

contingent could fail to exist
necessary cannot fail to exist
endless chain doesn't explain itself
doesn't depend on a beginning

Fine-tuning and morality

The fine-tuning argument notes that certain physical constants and quantities, such as the strength of gravity, the cosmological constant and the initial low entropy of the universe, fall within extraordinarily narrow ranges that permit life. Oxford mathematician John Lennox (God's Undertaker) argues that this looks like the work of a mind. The usual options are physical necessity, chance or design. Physics gives no known reason the constants had to be these values; chance at such odds is implausible; design is the best explanation. The most common reply is the multiverse, an enormous ensemble of universes, which is speculative, untestable so far, and itself needs fine-tuned mechanisms to generate universes.

Picture a control panel of dials, each set precisely; turn almost any slightly and stars, chemistry or life could not exist. (Entropy measures disorder; the universe began in extremely high order.) Sceptics often cite the anthropic principle: we could only observe a life-permitting universe, so why be surprised? But being unable to observe something is not the same as having nothing to explain. A man who survives a firing squad of fifty marksmen could not have observed his own death, yet he is right to ask why they all missed.

The moral argument, in Craig's form, says: if God does not exist, objective moral values and duties do not exist; objective moral values and duties do exist; therefore God exists. Objective here means true whether or not anyone believes it. C. S. Lewis used a version in Mere Christianity: we all appeal to a standard of fair play we did not invent and cannot escape. Atheists often grant premise 1 but deny premise 2; most people, however, cannot live as though torturing a child for fun is merely unfashionable.

Sharp atheists often reply with the Euthyphro dilemma, from Plato's Euthyphro: is something good because God commands it (so morality is arbitrary), or does God command it because it is good (so goodness is above God)? There is a third option. Goodness is grounded in God's own unchanging, holy character, and his commands express it (Lev 11:44; 1 John 1:5). God commands what is good because he himself is good.

Explain the fine-tuning argument's three options and why the multiverse reply is not a clear escape.Show answer

Certain constants and quantities, such as gravity's strength and the cosmological constant, fall within extremely narrow life-permitting ranges, and the explanation must be physical necessity, chance or design. Physics gives no known reason the values had to be what they are, and chance at such odds is implausible, so design is the best explanation. The multiverse reply is speculative and untestable so far, and the mechanism that would generate universes would itself need to be fine-tuned.

narrow life-permitting ranges
necessity, chance or design
design best explains
multiverse speculative and needs fine-tuning

Put the moral argument into one sentence you could say to a friend, and identify which premise atheists usually deny.Show answer

If there is no God, there are no objective moral values and duties, but there clearly are such values and duties, so God exists. Many atheists accept the first premise but deny the second. Yet most people cannot live as if torturing a child for fun is merely unfashionable, which shows they do recognise objective morality, as C. S. Lewis argued with our shared standard of fair play.

no God, no objective morals
objective morals exist
atheists deny premise 2
can't live as if cruelty is merely unfashionable

State the Euthyphro dilemma and explain the Christian answer to it.Show answer

The dilemma asks whether something is good because God commands it, which seems to make morality arbitrary, or whether God commands it because it is good, which seems to put goodness above God. Christians answer that there is a third option: goodness is grounded in God's own unchanging, holy character, and his commands express that character. So God commands what is good because he himself is good; morality is neither arbitrary nor above him.

good because commanded = arbitrary?
commanded because good = standard above God?
third option: God's nature is the standard
commands express his character

How would you answer someone who says the anthropic principle removes the need to explain fine-tuning?Show answer

The anthropic principle says we could only observe a life-permitting universe, so we should not be surprised to find one. But being unable to observe something is not the same as having no need to explain it. A man who survives a firing squad of fifty marksmen could not have observed his own death, yet he is right to ask why they all missed.

we could only observe a life-permitting universe
not observing is not the same as not needing an explanation
firing squad illustration

Using the arguments in conversation

In a real conversation you rarely present a formal syllogism and wait for a verdict. Start with a question that invites the person to think about the premise: “Do you think things can just pop into existence with no cause at all?” or “Why do you think there is something rather than nothing?” If the person agrees with a premise, you have common ground; if not, you have discovered what he actually believes, which is valuable.

Watch for the moment an objection reveals a deeper commitment. When someone says “maybe the universe just came from nothing” or “morality is just what my culture prefers”, he is not following evidence; he is protecting a worldview. Gently point that out, and ask whether he would accept that reasoning anywhere else in life.

Finally, do not overclaim. These arguments show that the universe has a transcendent, powerful, personal cause and that morality points to a holy Lawgiver. They do not by themselves show the Trinity or the cross. That is why the next lesson, on the resurrection, matters: the Creator has entered history and identified himself.

Example: Using the Kalam over coffee

Friend: I just don't see why the universe needs a God. It's just always been here.

You: Fair enough. Can I ask you something first? Do you think things can begin to exist with no cause at all?

Friend: No, I suppose not. Everything has a cause.

You: I'd say whatever begins to exist has a cause. So the big question is whether the universe began. Most cosmologists think the evidence points to a beginning, and if usable energy is running down, an infinitely old universe should have run down long ago.

Friend: OK, but then what caused God?

You: Good question. The argument is only about things that begin to exist. God, as Christians understand him, never began. Something has to exist without a beginning. The question is whether it's a universe that shows every sign of having started, or a Creator who is eternal.

Friend: Even so, that doesn't get you to Jesus.

You: You're right, it doesn't on its own. It gets us to a powerful, timeless, personal Creator. Christians believe that Creator has made himself known in history, above all by raising Jesus from the dead. Could we look at that next time?

Why is it often better to begin with a question than a formal syllogism, and what should you watch for in the other person's answers?Show answer

A question such as "Do you think things can just pop into existence with no cause?" invites the person to think about a premise; if he agrees you have common ground, and if not you learn what he actually believes. You should watch for the moment an objection reveals a deeper commitment, like "the universe came from nothing", because then he is protecting a worldview rather than following evidence. Gently point that out and ask whether he would reason that way anywhere else in life.

questions invite thinking
find common ground or real belief
objection reveals worldview
would you reason this way elsewhere?

What do the theistic arguments not prove on their own, and why does that matter?Show answer

They show that the universe has a transcendent, powerful, personal cause and that morality points to a holy Lawgiver, but they do not by themselves show the Trinity or the cross. We should not overclaim. That is why the resurrection matters: it shows that the Creator has entered history and identified himself.

don't overclaim
show a powerful personal cause
not Trinity or cross
resurrection identifies the Creator

Classical and presuppositional uses

A classical apologist uses these arguments as stage one: from neutral premises the unbeliever can accept, reason to the existence of a Creator, then move to the resurrection. The arguments are presented as probable or deductively valid conclusions from shared facts.

A presuppositionalist worries that this treats God as a hypothesis and hands the unbeliever the judge's chair. Van Til also argued that a merely probable “first cause” is not the self-sufficient, triune God of Scripture. Yet presuppositionalists like Frame affirm that the arguments are good if reframed: they are not neutral proofs but descriptions of what every person already knows, pressing the unbeliever with the evidence of Romans 1. The Kalam's premises, for example, rely on causality and the reliability of science, which themselves need God.

So you can use them together. Present the argument; when the sceptic attacks a premise by doubting causality or reason, show that only the Christian worldview can justify the causality and reason he is using. The evidential argument opens the door; the transcendental argument keeps it from being slammed shut. And always finish beyond a generic deity: the Creator has made himself known in Jesus Christ.

What is the difference between how a classical apologist and a presuppositionalist view the theistic arguments?Show answer

A classical apologist uses them as stage one, reasoning from neutral premises the unbeliever accepts to a Creator, then moving to the resurrection. A presuppositionalist worries this treats God as a hypothesis and puts the unbeliever in the judge's chair, and Van Til said a merely probable first cause is not the self-sufficient triune God of Scripture. Yet presuppositionalists like Frame accept the arguments when reframed as descriptions of what every person already knows, pressing home Romans 1.

classical: stage one from neutral premises
presup: God not a hypothesis
probable first cause isn't triune God
Frame: reframe as what people know

Explain how you could use a theistic argument and a transcendental argument together in one conversation.Show answer

You can present an argument like the Kalam, and when the sceptic attacks a premise by doubting causality or reason, you show that only the Christian worldview can justify the causality and reasoning he is using. In the section's words, the evidential argument opens the door and the transcendental argument keeps it from being slammed shut. Either way, finish beyond a generic deity by showing that the Creator has made himself known in Jesus Christ.

present the argument
doubting causality needs justification
door opened, kept open
finish with Christ

Key texts

Genesis 1:1: The universe had a beginning and a transcendent Creator, exactly what the Kalam concludes.
Psalm 19:1: Creation itself testifies to God's glory, the basis of natural theology.
Romans 1:20: God's eternal power and divine nature are clearly seen in what has been made, so people are without excuse.
Hebrews 1:3: Christ upholds all things by his word, grounding the contingency argument in the Son.
Romans 2:14-15: God's law is written on human hearts, explaining the universal moral sense the moral argument relies on.
Acts 14:15-17: Paul at Lystra points pagans to the Creator through rain and harvest, a model of reasoning from creation.

Objections and answers

Try answering each one yourself before you open the response.

“If everything needs a cause, then what caused God?”Show a response

The Kalam does not say everything needs a cause; it says whatever begins to exist needs a cause. God, by definition, did not begin to exist; he is eternal. The objection is like asking who wrote the unwritten book. Atheists historically held that the universe was eternal and uncaused, so they accepted the idea of something that exists without a cause; the question is only whether that something is the universe or God. Evidence that the universe had a beginning removes it from the running. And the contingency argument adds that something must exist necessarily, by its own nature, or nothing would exist at all. Asking for the cause of a necessary, eternal being misunderstands what the argument concludes.

“Quantum physics shows things can come into existence without a cause.”Show a response

Quantum events, such as virtual particles appearing in a vacuum, happen within a quantum vacuum, which is not nothing; it is a sea of energy governed by physical laws. Some quantum events may be indeterministic, meaning we cannot predict exactly when they happen, but that is different from being uncaused out of absolutely nothing. When physicists describe a universe arising “from nothing”, they usually mean from a prior physical state or from laws, which then need explaining. Absolute nothing has no properties, no potential and no laws. Premise 1 remains intuitive: being does not come from non-being. If it could, we should expect to see things popping into existence all the time, which we do not.

“The multiverse explains fine-tuning. With enough universes, one like ours is bound to happen.”Show a response

Three replies. First, the multiverse is speculative; we have no observational evidence of other universes, so invoking an untestable infinite ensemble to avoid design is not obviously more scientific than design. Second, proposed multiverse generators, such as inflationary models, would themselves require finely tuned laws and conditions, so the problem moves back a step. Third, as Roger Penrose and others have pointed out, if our universe were a random member of a multiverse, we should more likely observe a much smaller, simpler life-permitting region than the vast, ordered universe we actually see. Design remains the simplest explanation, and it fits what Scripture already says about a wise Creator.

“Morality evolved because it helped us survive. You don't need God.”Show a response

Evolution could perhaps explain why we feel certain moral impulses, but that is a different question from whether those impulses are true. If morality is just a survival strategy, then “rape is wrong” has the same status as “I prefer warm weather”: useful, perhaps, but not objectively binding. Ironically, an evolutionary story could undercut moral knowledge: our moral beliefs would have been selected for usefulness, not truth. Yet we cannot live like that; we condemn genocide as truly evil, not merely as unhelpful to gene survival. Christianity explains both the moral sense and its truth: we are made in the image of a holy God and his law is written on our hearts (Rom 2:15).

“Even if I grant a first cause, that's a long way from the God of the Bible. It could be Zeus, a deist god, or some impersonal force.”Show a response

You're right that these arguments don't prove everything, and I don't want to overclaim. But they do narrow the field a lot. A cause of all space, time and matter can't be part of the universe, so a god like Zeus, who lives inside the world and was himself born, isn't a candidate. The cause must be spaceless, timeless, immaterial and immensely powerful, and since it produced a universe with a beginning from a timeless state, it looks like a free, personal agent rather than a blind force. Fine-tuning and the moral argument add a mind and a holy Lawgiver. What the arguments can't tell us is whether this Creator has spoken or acted in history. That's why I'd like to look with you at the resurrection, where Christians believe the Creator identified himself in Jesus (Rom 1:4).

“These are just God-of-the-gaps arguments. Whenever science can't explain something, you plug in God. Science will close those gaps eventually.”Show a response

A god-of-the-gaps argument says, "We don't know how this works, so God did it." These arguments don't work that way. The Kalam rests on what we do know, such as Big Bang cosmology and the second law of thermodynamics, which point to a beginning. The contingency argument doesn't point to a missing link inside nature at all; it asks why there is a natural world in the first place, which is a question science assumes rather than answers. Fine-tuning starts from measured features of physics, not from ignorance: physics gives no known reason the constants had to have these values. Christians also don't think God only works in the gaps; Scripture says he upholds the whole universe by his word (Heb 1:3), so the regular processes science studies are his work too. Good science and belief in God are not competitors.

Written task

Choose one argument (Kalam, contingency, fine-tuning or moral). In 250-400 words, state it in premise form, defend each premise, answer the most common objection, and explain how you would use it as a Reformed apologist so that it points to the triune God of Scripture rather than a generic deity.

Hand this in to Mr Scott. He will look for:

States the argument accurately in valid premise form.
Supports each premise with clear reasons or evidence.
Answers a real, commonly raised objection fairly.
Explains how the argument fits with a presuppositional foundation.
Moves from the conclusion toward the God revealed in Christ.