Many arguments for and against the existence of God fall into one of the following categories: logical, empirical, metaphysical, subjective, or scientific. The same or comparable arguments are also frequently employed when discussing the possibility of many deities. The existence of God is a philosophical subject that encompasses the fields of ontology (the study of the essence of being or existence), epistemology (the nature and scope of knowing), and value theory (because some definitions of God include "perfection").
Plato and Aristotle established what are now known as cosmological arguments for the existence of a being that shapes the universe, known as the demiurge or the unmoved mover. These arguments marked the beginning of the Western tradition of philosophical discussion of the existence of God. Other arguments for God's existence have been put forth by René Descartes, who claimed that the existence of a good God is logically required for the evidence of the senses to have meaning; Thomas Aquinas, who offered his own version of the cosmological argument (the first way); and St. Anselm, who developed the first ontological argument.
The idea that God doesn't exist is known as atheism in philosophy, and more especially in the philosophy of religion. Jainism is one of the religions that denies the existence of a creator deity. Among the philosophers who have argued against the existence of God are Bertrand Russell, Ludwig Feuerbach, and David Hume. Among religious thinkers, theism—the belief that God exists—is the most prevalent viewpoint. 69.50% of philosophers of religion who participated in a 2020 PhilPapers survey said they accept or tend toward theism, compared to 19.86% who said they embrace or lean toward atheism.
In contrast to other ideas like theistic personalism, open theism, and process theism, classical theism describes God as the metaphysically ultimate being (the first, timeless, perfectly simple, and sovereign being, who is devoid of any anthropomorphic attributes). According to classical theists, God cannot be fully described. They think that defining God by human standards would go against his transcendent character. It appears difficult for a two-dimensional item to imagine three-dimensional humans, as Robert Barron demonstrates by analogy.
According to these traditions, God is also identified as the author (either directly or by inspiration) of some books, or as the source of communications from God (either directly or through dreams or omens), or as the cause of particular historical events. According to certain faiths, God is the one who is currently responding to pleas for help, knowledge, or viewpoints.
Pantheism holds that the universe and God are one and the same. According to this perspective, the study of God's nature is the fundamental purpose of the natural sciences. The philosophical conundrum that arises from this conception of God is that, except from the terminology employed to characterize it, a cosmos with and without God are identical.
According to deism and panentheism, there is a God that is separate from the universe or that transcends it in space, time, or some other manner. These viewpoints reject the idea that God personally communicates with mankind or interferes in the way the cosmos functions. It is difficult, if not impossible, to discern between a universe with and one without God if one believes that God never interacts with the universe, communicates with it, or may have evolved into the universe (as in pandeism).
One issue raised by the existence of God is that conventional wisdom typically attributes to him a variety of miraculous abilities. As demonstrated in the story of Baucis and Philemon, supernatural beings may have the ability to hide and disclose themselves for their own ends. Furthermore, conceptions of God hold that God is the ultimate creator of nature and the laws of science rather than a component of the natural order. Therefore, according to Aristotelian philosophy, God is a component of the explanatory framework required to substantiate scientific findings, and any abilities God may have are closely related to the natural order that results from God's role as the creator of nature (see also Monadology).
Scientists follow the scientific method, which calls for empirical study to support hypotheses. The overwhelming majority of popular conceptions of God either explicitly or implicitly claim the existence of an unprovable deity. Therefore, by definition, the existence of God might be outside the purview of modern science. It is the "natural light of human reason" that the Catholic Church claims reveals the reality of God. Fideists argue that belief in God's existence, which may not be provable or arguable, is based solely on faith. According to John Polkinghorne, the concepts of quantum mechanics, which appear contradictory but explain a wide range of divergent facts, are the closest science approximation to the existence of God. Alvin Plantinga asserts that both the existence of God and the existence of other minds are infamously hard to "prove" against a resolute skeptic.
One method proposed by authors like Stephen D. Unwin is to treat (specific forms of) naturalism and theism as two Bayesian hypotheses, listing specific data (or purported data) about the world and implying that the likelihood of these data is substantially higher under one hypothesis than the other. It is possible to interpret the majority of arguments for or against God's existence as pointing to specific features of the cosmos. Wittgenstein and other philosophers have an anti-realist stance and reject intellectual arguments concerning the existence of God. Charles Taylor, for example, argues that the real is whatever is unavoidable. Perhaps God is as real as anything else if we are unable to disprove it, replace it, or reduce discussions about him to anything else.
The core of Vedanta epistemology is existence in absolute truth. Conventional methods based on sense perception were questioned as potentially deceptive because of predetermined or superimposed notions. Even in the nastika traditions of Mayavada schools that follow Adi Shankara, the existence of the doubter persists, despite the fact that all object-cognition is subject to doubt. Beginning with God or Isvara, the Ultimate Reality, the five eternal truths to be examined under ontology cannot be demonstrated by logic alone and frequently call for greater proof.
In Vaisnavism, the personal absolute God of the Western faiths is identified with Vishnu or his intimate ontological form of Krishna. Three fundamental characteristics of Krishna's form—"eternal existence" or sat, which is associated with the brahman aspect; "knowledge" or chit, which is associated with the paramatman; and "bliss" or ananda in Sanskrit, which is associated with bhagavan—are the basis for understanding aspects of Krishna as svayam bhagavan in the original Absolute Truth, sat chit ananda.