Philosophers and theologians have proposed several influential arguments for God’s existence throughout centuries, each with key proponents, philosophical details, and enduring influence. Below you’ll find a summary and expansion of the most prominent arguments.

1. Cosmological Argument

Summary:
The universe exists, and everything that exists has a cause. There must be a “First Cause” outside of the series of causes—this cause is identified as God.

Supporting Points:

• Whatever begins to exist has a cause.

• The universe began to exist (supported philosophically and by the Big Bang theory).

• Therefore, the universe has a cause. This cause must be outside space and time, uncaused and eternal.

Variants:

• Kalam Cosmological Argument: Refined by Islamic philosopher Al-Ghazali and popularized by William Lane Craig, focusing on the universe having a beginning.

• Aquinas’ Five Ways: Includes arguments from motion, causality, and contingency, all forms of cosmological reasoning.

Key Proponents:

• Aristotle (First Mover)

• Thomas Aquinas (Five Ways)

• Al-Ghazali (Kalam)

• William Lane Craig (contemporary defender)

Famous Formulation:

• “Whatever begins to exist has a cause; the universe began to exist; therefore, the universe has a cause.”123

2. Teleological Argument (Argument from Design)

Summary:
The universe shows signs of order, purpose, and complexity that suggest an intelligent designer.

Supporting Points:

• The precise constants of nature and biological complexity are seen as improbable by chance.

• Paley’s watchmaker analogy: A watch’s complexity implies a watchmaker; the universe’s order implies a creator.

Key Proponents:

• William Paley (watch analogy)

• Aquinas (Fifth Way)

• Modern proponents include proponents of Intelligent Design

Critics:

• David Hume (challenged analogy and probability)

• Charles Darwin (natural selection as an alternative explanation)

Notable Formulation:

• “Because the order of the universe cannot be the result of chance, design and purpose must be at work, implying divine intelligence.”453

3. Ontological Argument

Summary:

God is defined as the greatest conceivable being. If it is possible for God to exist, He must exist—because existence in reality is greater than existence only in the mind.

Supporting Points:

• Uses pure reason rather than empirical evidence.

• Focuses on the concept and definition of God.

Key Proponents:

• Anselm of Canterbury (original argument)

• René Descartes (19th-century reformulation)

• Alvin Plantinga (modern modal version)

Famous Formulation:

• “That than which nothing greater can be conceived exists both in the mind and in reality.”678

Criticism:

• Immanuel Kant: Existence is not a predicate.

4. Moral Argument

Summary:
Universal moral values and duties require a transcendent source. Without God, there would be no objective morality.

Supporting Points:

• There are universally recognized rights and wrongs.

• Moral objectivity is difficult to explain without a moral lawgiver.

Key Proponents:

• Immanuel Kant (moral law within points to a moral lawgiver)

• C.S. Lewis (popular apologetics)

• William Lane Craig (contemporary defense)

Typical Formulation:

• “If God does not exist, objective moral values do not exist; objective moral values do exist; therefore, God exists.”259

5. Argument from Contingency (Necessary Being)

Summary:
Everything in the universe is contingent (could or could not exist), but there must be a necessary being that grounds the existence of contingent things.

Supporting Points:

• Universe is a chain of contingent beings—must be traced to a necessary being.

• Influential in medieval Islamic, Jewish, and Christian philosophy.

Key Proponents:

• Avicenna (Ibn Sina) – “Proof of the Truthful”

• Aquinas (Third Way)

• Gottfried Wilhelm Leibniz

Core Idea:

• “Contingent beings exist; they need explanation outside themselves—a necessary being (God).”110

6. Transcendental Argument

Summary:
Rational thought, order, and logic presuppose God’s existence. Without God, these concepts have no foundation.

Key Proponents:

• Cornelius Van Til (presuppositional apologetics)

• Greg Bahnsen

Key Point:

• “Without God, we have no basis for or explanation of order, logic, or reason.”5

Overview Table