Existence of God

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 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 and ontology and the theory of value.
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 ; 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, and more specifically in 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:

Strong theist. 100% probability that God exists. In the words of Carl G. Jung: "I do not believe, I know."
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."
Leaning towards theism. Higher than 50% but not very high. "I am very uncertain, but I am inclined to believe in God."
Completely impartial. Exactly 50%. "God's existence and nonexistence are exactly equiprobable."
Leaning towards atheism. Lower than 50% but not very low. "I do not know whether God exists but I'm inclined to be skeptical."
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."
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, 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, 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 of certain texts, or that certain texts describe specific historical events caused by the God in question or communications from God. Some traditions also believe that God is the entity which is currently answering prayers for intervention or information or opinions.
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". 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 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 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, 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: preambles of faith and 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, emerged in the late 1920s. This school was instituted by Cornelius Van Til, and came to be popularly called presuppositional apologetics. 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 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 rather than directly. 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 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, 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.