The existence of God is a subject of debate in the philosophy of religion and theology. A wide variety of arguments for and against the existence of God (with the same or similar arguments also generally being used when talking about the existence of multiple deities) can be categorized as logical, empirical, metaphysical, subjective, or scientific. In philosophical terms, the question of the existence of God involves the disciplines of epistemology (the nature and scope of knowledge) and ontology (study of the nature of being or existence) and the theory of value (since some definitions of God include perfection).

The Western tradition of philosophical discussion of the existence of God began with Plato and Aristotle, who made arguments for the existence of a being responsible for fashioning the universe, referred to as the demiurge or the unmoved mover, that today would be categorized as cosmological arguments. Other arguments for the existence of God have been proposed by St. Anselm, who formulated the first ontological argument; Thomas Aquinas, who presented his own version of the cosmological argument (the first way); René Descartes, who said that the existence of a benevolent God is logically necessary for the evidence of the senses to be meaningful. John Calvin argued for a sensus divinitatis, which gives each human a knowledge of God's existence. Islamic philosophers who developed arguments for the existence of God comprise Averroes, who made arguments influenced by Aristotle's concept of the unmoved mover; Al-Ghazali and Al-Kindi, who presented the Kalam cosmological argument; Avicenna, who presented the Proof of the Truthful; and Al-Farabi, who made Neoplatonic arguments.

In philosophy, specifically the philosophy of religion, atheism refers to the proposition that God does not exist. Some religions, such as Jainism, reject the possibility of a creator deity. Philosophers who have provided arguments against the existence of God include David Hume, Ludwig Feuerbach, and Bertrand Russell.

Theism, the proposition that God exists, is the dominant view among philosophers of religion. In a 2020 PhilPapers survey, 69.50% of philosophers of religion stated that they accept or lean towards theism, while 19.86% stated they accept or lean towards atheism. However, philosophers as a whole tend to be more skeptical of God’s existence: the same survey found that 66.72% of all philosophers surveyed accepted or leaned towards atheism, while 18.64% accepted or leaned towards theism. Prominent contemporary philosophers of religion who defended theism include Alvin Plantinga, Yujin Nagasawa, John Hick, Richard Swinburne, and William Lane Craig, while those who defended atheism include Graham Oppy, Paul Draper, Quentin Smith,

J. L. Mackie, and J. L. Schellenberg.

Positions

Positions on the existence of God can be divided along numerous axes, producing a variety of orthogonal classifications. Theism and atheism are positions of belief or lack of it, while gnosticism and agnosticism are positions of knowledge or the lack of it. Ignosticism concerns belief about God's conceptual coherence. Apatheism concerns belief about the practical importance of whether God exists.

For the purposes of discussion, Richard Dawkins described seven "milestones" on his spectrum of theistic probability:

  1. Strong theist. 100% probability that God exists. In the words of Carl G. Jung: "I do not believe, I know."
  2. De facto theist. Very high probability but short of 100%. "I don't know for certain, but I strongly believe in God and live my life on the assumption that he is there."
  3. Leaning towards theism. Higher than 50% but not very high. "I am very uncertain, but I am inclined to believe in God."
  4. Completely impartial. Exactly 50%. "God's existence and nonexistence are exactly equiprobable."
  5. Leaning towards atheism. Lower than 50% but not very low. "I do not know whether God exists but I'm inclined to be skeptical."
  6. De facto atheist. Very low probability, but short of zero. "I don't know for certain but I think God is very improbable, and I live my life on the assumption that he is not there."
  7. Strong atheist. "I know there is no God, with the same conviction as Jung knows there is one."

Theism

The Catholic Church, following the teachings of Paul the Apostle (e.g., ), Thomas Aquinas, and the First Vatican Council, affirms that God's existence "can be known with certainty from the created world by the natural light of human reason".

Traditional religious definition of God

In classical theism, God is characterized as the metaphysically ultimate being (the first, timeless, absolutely simple and sovereign being, who is devoid of any anthropomorphic qualities), in distinction to other conceptions such as theistic personalism, open theism, and process theism. Classical theists do not believe that God can be completely defined. They believe it would contradict the transcendent nature of God for mere humans to define him. Robert Barron explains by analogy that it seems impossible for a two-dimensional object to conceive of three-dimensional humans.

In modern Western societies, the concepts of God typically entail a monotheistic, supreme, ultimate, and personal being, as found in the Christian, Islamic and Jewish traditions. In monotheistic religions outside the Abrahamic traditions, the existence of God is discussed in similar terms. In these traditions, God is also identified as the author (either directly or by inspiration) of certain texts, or that certain texts describe specific historical events caused by the God in question or communications from God (whether in direct speech or via dreams or omens). Some traditions also believe that God is the entity which is currently answering prayers for intervention or information or opinions.thumb|Ibn Rushd, a 12th-century Islamic scholar

Many Islamic scholars have used philosophical and rational arguments to prove the existence of God. For example, Ibn Rushd, a 12th-century Islamic scholar, philosopher, and physician, states there are only two arguments worthy of adherence, both of which are found in what he calls the "Precious Book" (The Qur'an). Rushd cites "providence" and "invention" in using the Qur'an's parables to claim the existence of God. Rushd argues that the Earth's weather patterns are conditioned to support human life; thus, if the planet is so finely-tuned to maintain life, then it suggests a fine tuner—God. The Sun and the Moon are not just random objects floating in the Milky Way, rather they serve us day and night, and the way nature works and how life is formed, humankind benefits from it. Rushd essentially comes to a conclusion that there has to be a higher being who has made everything perfectly to serve the needs of human beings.

Moses ben Maimon, widely known as Maimonides, was a Jewish scholar who tried to logically prove the existence of God. Maimonides offered proofs for the existence of God, but he did not begin with defining God first, like many others do. Rather, he used the description of the Earth and the universe to prove the existence of God. He talked about the Heavenly bodies and how they are committed to eternal motion. Maimonides argued that because every physical object is finite, it can only contain a finite amount of power. If everything in the universe, which includes all the planets and the stars, is finite, then there has to be an infinite power to push forth the motion of everything in the universe. Narrowing down to an infinite being, the only thing that can explain the motion is an infinite being (meaning God) which is neither a body nor a force in the body. Maimonides believed that this argument gives us a ground to believe that God is, not an idea of what God is. He believed that God cannot be understood or be compared.

Non-personal definitions of God

In pantheism, God and the universe are considered to be the same thing. In this view, the natural sciences are essentially studying the nature of God. This definition of God creates the philosophical problem that a universe with God and one without God are the same, other than the words used to describe it.

Deism and panentheism assert that there is a God distinct from, or which extends beyond (either in time or in space or in some other way) the universe. These positions deny that God intervenes in the operation of the universe, including communicating with humans personally. The notion that God never intervenes or communicates with the universe, or may have evolved into the universe (as in pandeism), makes it difficult, if not by definition impossible, to distinguish between a universe with God and one without.

The Ethics of Baruch Spinoza gave two demonstrations of the existence of God. The God of Spinoza is uncaused by any external force and has no free will, it is not personal and not anthropomorphic.

Debate about how theism should be argued

In Christian faith, theologian and philosopher Thomas Aquinas made a distinction between: (a) preambles of faith and (b) articles of faith. The preambles include alleged truths contained in revelation which are nevertheless demonstrable by reason, e.g., the immortality of the soul, the existence of God. The articles of faith, on the other hand, contain truths that cannot be proven or reached by reason alone and presuppose the truths of the preambles, e.g., in Christianity, the Holy Trinity, is not demonstrable and presupposes the existence of God.

The argument that the existence of God can be known to all, even prior to exposure to any divine revelation, predates Christianity. Paul the Apostle made this argument when he said that pagans were without excuse because "since the creation of the world God's invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made". In this, Paul alludes to the proofs for a creator, later enunciated by Thomas Aquinas and others, that had also been explored by the Greek philosophers.

Another apologetical school of thought, including Dutch and American Reformed thinkers (such as Abraham Kuyper, Benjamin Warfield, and Herman Dooyeweerd), emerged in the late 1920s. This school was instituted by Cornelius Van Til, and came to be popularly called presuppositional apologetics (though Van Til felt "transcendental" would be a more accurate title). The main distinction between this approach and the more classical evidentialist approach is that the presuppositionalist denies any common ground between the believer and the non-believer, except that which the non-believer denies, namely, the assumption of the truth of the theistic worldview. In other words, presuppositionalists do not believe that the existence of God can be proven by appeal to raw, uninterpreted, or "brute" facts, which have the same (theoretical) meaning to people with fundamentally different worldviews, because they deny that such a condition is even possible. They claim that the only possible proof for the existence of God is that the very same belief is the necessary condition to the intelligibility of all other human experience and action. They attempt to prove the existence of God by means of appeal to the transcendental necessity of the belief—indirectly (by appeal to the unavowed presuppositions of the non-believer's worldview) rather than directly (by appeal to some form of common factuality). In practice, this school uses what have come to be known as transcendental arguments. These arguments claim to demonstrate that all human experience and action (even the condition of unbelief, itself) is a proof for the existence of God, because God's existence is the necessary condition of their intelligibility.

Protestant Christians note that the Christian faith teaches "salvation is by faith", and that faith is reliance upon the faithfulness of God. The most extreme example of this position is called fideism, which holds that faith is simply the will to believe, and argues that if God's existence were rationally demonstrable, faith in its existence would become superfluous. Søren Kierkegaard argued that objective knowledge, such as 1+1=2, is unimportant to existence. If God could rationally be proven, his existence would be unimportant to humans. It is because God cannot rationally be proven that his existence is important to us. In The Justification of Knowledge, the Calvinist theologian Robert L. Reymond argues that believers should not attempt to prove the existence of God. Since he believes all such proofs are fundamentally unsound, believers should not place their confidence in them, much less resort to them in discussions with non-believers; rather, they should accept the content of revelation by faith. Reymond's position is similar to that of his mentor Gordon Clark, which holds that all worldviews are based on certain unprovable first premises (or, axioms), and therefore are ultimately unprovable. The Christian theist therefore must simply choose to start with Christianity rather than anything else, by a "leap of faith". This position is also sometimes called presuppositional apologetics, but should not be confused with the Van Tillian variety.

Atheism

In the philosophy of religion, atheism is standardly defined as the metaphysical claim that God does not exist. In 1972, Antony Flew proposed defining atheism as the psychological state of lacking any belief in God. However, Flew's definition is usually rejected, due to the need for a name for the direct opposite proposition to theism, the metaphysical claim that God does exist. The strong atheist explicitly asserts the non-existence of gods.

Negative atheism

Negative atheism (also called "weak atheism" and "soft atheism") is a proposed form of atheism other than positive, wherein a person does not believe in the existence of any deities, but does not explicitly assert there to be none. Agnosticism does not define one's belief or disbelief in gods; agnostics may still identify themselves as theists or atheists.

Strong agnosticism

Strong agnosticism is the belief that it is impossible for humans to know whether or not any deities exist.

Weak agnosticism

Weak agnosticism is the belief that the existence or nonexistence of deities is unknown but not necessarily unknowable.

Agnostic theism

Agnostic theism is the philosophical view that encompasses both theism and agnosticism. An agnostic theist believes in the existence of a god or God, but regards the basis of this proposition as unknown or inherently unknowable. Agnostic theists may also insist on ignorance regarding the properties of the gods they believe in.

Agnostic atheism

Agnostic atheism is a philosophical position that encompasses both atheism and agnosticism. Agnostic atheists are atheistic because they do not hold a belief in the existence of any deity and agnostic because they claim that the existence of a deity is either unknowable in principle or currently unknown in fact.

The theologian Robert Flint explains:

Apatheism

An apatheist is someone who is not interested in accepting or denying any claims that gods exist or do not exist. An apatheist lives as if there are no gods and explains natural phenomena without reference to any deities. The existence of gods is not rejected, but may be designated unnecessary or useless; gods neither provide purpose to life, nor influence everyday life, according to this view.

Ignosticism

The ignostic (or igtheist) usually concludes that the question of God's existence or nonexistence is usually not worth discussing because concepts like "God" are usually not sufficiently or clearly defined. Ignosticism or igtheism is the theological position that every other theological position (including agnosticism and atheism) assumes too much about the concept of God and many other theological concepts. It can be defined as encompassing two related views about the existence of God. The view that a coherent definition of God must be presented before the question of the existence of God can be meaningfully discussed. Furthermore, if that definition is unfalsifiable, the ignostic takes the theological noncognitivist position that the question of the existence of God (per that definition) is meaningless. In this case, the concept of God is not considered meaningless; the term "God" is considered meaningless. The second view is synonymous with theological noncognitivism, and skips the step of first asking "What is meant by 'God'?" before proclaiming the original question "Does God exist?" as meaningless.

Some philosophers have seen ignosticism as a variation of agnosticism or atheism, while others have considered it to be distinct. An ignostic maintains that he cannot even say whether he is a theist or an atheist until a sufficient definition of theism is put forth.

The term "ignosticism" was coined in the 1960s by Sherwin Wine, a rabbi and a founding figure of Humanistic Judaism. The term "igtheism" was coined by the secular humanist Paul Kurtz in his 1992 book The New Skepticism.

Philosophical issues

The problem of the supernatural

One problem posed by the question of the existence of God is that traditional beliefs usually ascribe to God various supernatural powers. Supernatural beings may be able to conceal and reveal themselves for their own purposes, as for example in the tale of Baucis and Philemon. In addition, according to concepts of God, God is not part of the natural order, but the ultimate creator of nature and of the scientific laws. Thus in Aristotelian philosophy, God is viewed as part of the explanatory structure needed to support scientific conclusions and any powers God possesses are—strictly speaking—of the natural order that is derived from God's place as originator of nature (see also Monadology).

In Karl Popper's philosophy of science, belief in a supernatural God is outside the natural domain of scientific investigation because all scientific hypotheses must be falsifiable in the natural world. The non-overlapping magisteria view proposed by Stephen Jay Gould also holds that the existence (or otherwise) of God is irrelevant to and beyond the domain of science.

Scientists follow the scientific method, within which theories must be verifiable by physical experiment. The majority of prominent conceptions of God explicitly or effectively posit a being whose existence is not testable either by proof or disproof. Therefore, the question of God's existence may lie outside the purview of modern science by definition. The Catholic Church maintains that knowledge of the existence of God is the "natural light of human reason". Fideists maintain that belief in God's existence may not be amenable to demonstration or refutation, but rests on faith alone.

Logical positivists such as Rudolf Carnap and A. J. Ayer viewed any talk of gods as literal nonsense. For the logical positivists and adherents of similar schools of thought, statements about religious or other transcendent experiences can not have a truth value, and are deemed to be without meaning, because such statements do not have any clear verification criteria. As the Christian biologist Scott C. Todd put it "Even if all the data pointed to an intelligent designer, such a hypothesis is excluded from science because it is not naturalistic." This argument limits the domain of science to the empirically observable and limits the domain of God to the empirically unprovable.

Nature of relevant proofs and arguments

John Polkinghorne suggests that the nearest analogy to the existence of God in physics is the ideas of quantum mechanics which are seemingly paradoxical but make sense of a great deal of disparate data.

Alvin Plantinga compares the question of the existence of God to the question of the existence of other minds, claiming both are notoriously impossible to "prove" against a determined skeptic.

One approach, suggested by writers such as Stephen D. Unwin, is to treat (particular versions of) theism and naturalism as though they were two hypotheses in the Bayesian sense, to list certain data (or alleged data), about the world, and to suggest that the likelihoods of these data are significantly higher under one hypothesis than the other. Most of the arguments for, or against, the existence of God can be seen as pointing to particular aspects of the universe in this way. In almost all cases it is not seriously suggested by proponents of the arguments that they are irrefutable, merely that they make one worldview seem significantly more likely than the other. However, since an assessment of the weight of evidence depends on the prior probability that is assigned to each worldview, arguments that a theist finds convincing may seem thin to an atheist and vice versa.

Philosophers, such as Wittgenstein, take a view that is considered anti-realist and oppose philosophical arguments related to God's existence. For instance, Charles Taylor contends that the real is whatever will not go away. If we cannot reduce talk about God to anything else, or replace it, or prove it false, then perhaps God is as real as anything else.

In George Berkeley's A Treatise Concerning the Principles of Human Knowledge of 1710, he argued that a "naked thought" cannot exist, and that a perception is a thought; therefore only minds can be proven to exist, since all else is merely an idea conveyed by a perception. From this Berkeley argued that the universe is based upon observation and is non-objective. However, he noted that the universe includes "ideas" not perceptible to humankind, and that there must, therefore, exist an omniscient superobserver, which perceives such things. Berkeley considered this proof of the existence of the Christian god.

Outside of Western thought

Existence in absolute truth is central to Vedanta epistemology. Traditional sense perception based approaches were put into question as possibly misleading due to preconceived or superimposed ideas. But though all object-cognition can be doubted, the existence of the doubter remains a fact even in nastika traditions of mayavada schools following Adi Shankara. The five eternal principles to be discussed under ontology, beginning with God or Isvara, the Ultimate Reality cannot be established by the means of logic alone, and often require superior proof.

In Vaisnavism Vishnu, or his intimate ontological form of Krishna, is equated to the personal absolute God of the Western traditions. Aspects of Krishna as svayam bhagavan in original Absolute Truth, sat chit ananda, are understood originating from three essential attributes of Krishna's form, i.e., "eternal existence" or ', related to the brahman aspect; "knowledge" or chit, to the paramatman; and "bliss" or ananda in Sanskrit, to bhagavan.

Arguments

Arguments for the existence of God

Logical arguments

Aquinas' Five Ways

In article 3, question 2, first part of his Summa Theologica, Thomas Aquinas developed his five arguments for God's existence. These arguments are grounded in an Aristotelian ontology and make use of the infinite regression argument. Aquinas did not intend to fully prove the existence of God as he is orthodoxly conceived (with all of his traditional attributes), but proposed his Five Ways as a first stage, which he built upon later in his work. Aquinas' Five Ways argued from the unmoved mover, first cause, necessary being, argument from degree, and the argument from final cause.

One type of cosmological, or "first cause" argument, typically called the Kalam cosmological argument, asserts that since everything that begins to exist has a cause, and the universe began to exist, the universe must have had a cause which was itself not caused. This ultimate first cause is identified with God. Christian apologist William Lane Craig gives a version of this argument in the following form:

  1. Whatever begins to exist has a cause.
  2. The Universe began to exist.
  3. Therefore, the Universe had a cause.
Ontological argument

The ontological argument has been formulated by philosophers including St. Anselm and René Descartes. The argument proposes that God's existence is self-evident. The logic, depending on the formulation, reads roughly as follows: