In theology, the doctrine of divine simplicity says that God is without parts. The general idea of divine simplicity can be stated in this way: the being of God is identical to the "attributes" of God. In other words, such characteristics as omnipresence, goodness, truth, eternity, etc. are identical to God's being, not qualities that make up that being, nor abstract entities inhering in God as in a substance. Varieties of the doctrine may be found in Jewish, Christian, and Muslim philosophical theologians, especially during the heyday of scholasticism, though the doctrine's origins may be traced back to ancient Greek thought.

In classical Christian theism, God is simple, not composite, not made up of thing upon thing. In other words, the characteristics of God are not parts of God that together make up God. Because God is simple, God is those characteristics; for example, God does not have goodness, but simply is goodness. For typical Christian theologians, divine simplicity does not entail that the attributes of God are indistinguishable to thought. It is no contradiction of the doctrine to say, for example, that God is both just and merciful. Thomas Aquinas, for instance, in whose system of thought the idea of divine simplicity is central, wrote in Summa Theologica that because God is infinitely simple, God can only appear to the finite mind as infinitely complex.^{[citation needed]}

William Lane Craig (born August 23, 1949) is an American analytic philosopher, philosophical theologian, and Christian apologist. He is known for his work in the philosophy of religion, philosophy of time, and the defense of Christian theism. One of his most notable contributions to the philosophy of religion is his defense of the Kalām cosmological argument, which is the most widely discussed argument for the existence of God in contemporary Western philosophy. In theology, he has also defended Molinism and the belief that God is, since Creation, subject to time.

Craig has authored or edited over 30 books, including The Kalām Cosmological Argument (1979), The Cosmological Argument from Plato to Leibniz (1980), Theism, Atheism, and Big Bang Cosmology (with Quentin Smith, 1993), Philosophical Foundations for a Christian Worldview (with J.P. Moreland, 2003) and Reasonable Faith: Christian Truth and Apologetics (3d edition, 2008).

Craig received a Bachelor of Arts degree in communications from Wheaton College, Illinois, in 1971 and two summa cum laude master's degrees from Trinity Evangelical Divinity School in Deerfield, Illinois, in 1975, in philosophy of religion and ecclesiastical history. He earned a Ph.D. in philosophy under John Hick at the University of Birmingham, England in 1977 and a Th.D. under Wolfhart Pannenberg at the University of Munich in 1984.

William Lane (6 September 1861 – 26 August 1917) was a journalist, advocate of Australian labour politics and a utopian.

Lane was born in Bristol, England, eldest son of James Lane, from Ireland a Protestant Master Gardener, and his English wife Caroline, née Hall. When Lane was born his father was earning a miserable wage, but later his circumstances improved and he became an employer. The boy was educated at Bristol Grammar School and showed ability, but he was sent early to work as an office boy. Lane's mother died when he was 14 years of age, and at age 16 he migrated to Canada, then to the United States, where he worked first as a printer, then as a reporter for the Detroit Free Press (1881), there meeting his future wife Ann MacGuire. In 1885 they migrated to Brisbane, Australia, where Lane immediately got work as a feature writer for the weekly newspaper Queensland Figaro, then as a columnist for the newspapers Brisbane Courier and Evening Telegraph, using a number of pseudonyms ("Lucinda Sharpe", which some consider to be the work of Annie Lane, William Wilcher and "Sketcher").

Gordon Haddon Clark (August 31, 1902 – April 9, 1985) was an American philosopher and Calvinist theologian. He was a primary advocate for the idea of presuppositional apologetics and was chairman of the Philosophy Department at Butler University for 28 years. He was an expert in pre-Socratic and ancient philosophy and was noted for his rigor in defending propositional revelation against all forms of empiricism and rationalism, in arguing that all truth is propositional and in applying the laws of logic. His theory of knowledge is sometimes called scripturalism.

Clark was raised in a Christian home and studied Calvinist thought from a young age. In 1924, he graduated from the University of Pennsylvania with a bachelor's degree in French and earned his doctorate in Philosophy from the same institution in 1929. The following year, he studied at the Sorbonne.

He began teaching at the University of Pennsylvania after receiving his bachelor's degree and also taught at Reformed Episcopal Seminary in Philadelphia. In 1936, he accepted a professorship in Philosophy at Wheaton College, Illinois, where he remained until 1943, when he accepted the Chairmanship of the Philosophy Department at Butler University in Indianapolis. In 1973, he retired from Butler University and taught at Covenant College in Lookout Mountain, Georgia, and Sangre de Cristo Seminary in Westcliffe, Colorado.

Basil of Caesarea, also called Saint Basil the Great, (329 or 330 – January 1, 379) (Greek: Ἅγιος Βασίλειος ὁ Μέγας) was the Greek bishop of Caesarea Mazaca in Cappadocia, Asia Minor (modern-day Turkey). He was an influential theologian, who supported the Nicene Creed and opposed the heresies of the early Christian Church, fighting against both Arianism and the followers of Apollinaris of Laodicea. His ability to balance his theological convictions with his political connections made Basil a powerful advocate for the Nicene position.

In addition to his work as a theologian, Basil was known for his care of the poor and underprivileged. Basil established guidelines for monastic life which focus on community life, liturgical prayer, and manual labour. Together with Pachomius he is remembered as a father of communal monasticism in Eastern Christianity. He is considered a saint by the traditions of both Eastern and Western Christianity.

Basil, Gregory of Nazianzus, and Gregory of Nyssa are collectively referred to as the Cappadocian Fathers. The Eastern Orthodox Church and Eastern Catholic Churches have given him, together with Gregory of Nazianzus and John Chrysostom, the title of Great Hierarch. His is recognised as a Doctor of the Church in both Eastern Orthodoxy and Roman Catholicism. He is sometimes referred to by the epithet "Ουρανοφαντωρ", translatable as "revealer of heavenly mysteries".