THEISM, in the broadest sense, means belief in God. The word, however, is used generally with the implication that the belief is held in a conscious and rational manner, and hence Theism is usually applied only to a system of beliefs which has some claim to be regarded as a philosophy. According to the Oxford Dictionary the first occurrence of the word is in Cud worth's Intellectual System of the Universe (1678). The ety mology of the word (0€6s) would suggest that it might cover any conception of the universe which admitted the existence of Deity; but in practice Theism has come to mean a belief in one God, and the word is not easily distinguished from Monotheism, save that Theism has a more theoretical implication.
Theism as a philosophical and theological position may be dis tinguished from other theories. It is, of course, the direct antith esis to Atheism (q.v.), which, strictly speaking, is the denial that God exists. It is to be distinguished, again, from Agnosticism (q.v.), the view that there is no sufficient ground for either an affirmative or negative answer to the question: Does God exist? and that the only rational attitude is absolute suspense of judg ment. It should be observed, however, that there is a sense of the word Agnosticism which is not wholly incompatible with Theistic belief. The theory of Herbert Spencer, that we can know that an Ultimate Reality exists but can also know that that Reality is unknowable, is sometimes described as agnosticism. Herbert Spencer's theory, as it stands, is plainly absurd, because in order to know that the Ultimate Reality is unknowable we must know enough of the nature of the Unknowable to be justified in mak ing this assertion about it. All reflective Theists would acknowl edge, however, that there is an element of truth in the Agnostic position—the human mind is incapable of grasping completely the nature of the Divine, and though there is a genuine knowledge of God, for finite mind that knowledge must always be incom plete. It is customary to distinguish Theism from Deism (q.v.).
The Deists were writers on natural religion in the 18th century who shared the desire to set religion on a purely rational basis and tended, in a greater or less degree, to exclude the ideas of revelation and mystery, reducing Christianity to those truths which, it was alleged, could be attained by the unaided reason. Though some of these authors had pantheistic tendencies, the name Deism has been given to that type of theology which con siders God and the world to be absolutely distinct from one another, thus conceiving the Deity as an external Creator and Governor. In the language of modern philosophy Deism is the view which emphasises the transcendence of God but denies His immanence. In contrast to Deism, Theism affirms the presence of God in the world, holding both immanence and transcendence. Pantheism (q.v.) presents a contrast to Theism of the opposite kind to that which we have found in Deism. Pantheistic systems,
though widely different from one another in spirit and presenta tion, agree in making an identification between God and the Universe. It is sometimes said that Pantheism maintains divine immanence while eliminating from its creed every vestige of divine transcendence. This manner of expression, though open to criticism, has the merit of making clear the main difference be tween Pantheism and both Deism and Theism. Certain philo sophical systems may be classified for this purpose under the head of Pantheism. Spinoza's philosophy of God as the Infinite Sub stance and some forms of Absolute Idealism, as for example, that represented in England by the late F. H. Bradley cannot be de scribed as theistic in the narrow sense of that word and are, theologically considered, pantheistic in tendency. Dualism is to be regarded as another theory which, in some of its forms, has affinities with Theism but is in essence different. Properly, Dual ism means a view of the world which attributes its existence to two different or possibly antagonistic principles both equally ultimate, whether those principles be conceived as two deities, as in some forms of Zoroastrianism, or God and matter as in Manichaeism. A modified Dualism enters into most Theistic theories, but no theory could be called fully Theistic which was satisfied with a final Dualism.
We may now proceed to state in a positive manner the general tenets of Theism. It must be remembered that pure Theism has never been a widely influential religious belief. In the historical religions Theism is mixed with other elements, or rather perhaps is the basis of them. Thus Christianity is a Theistic religion, but its distinctive characteristic is the doctrine of the Incarnation. In the same way, Mohammedanism is Theism modified by special beliefs about the revelation of Allah through Mohammed. The fundamental conception of Theism in all its developed forms is that of a Being who is at once the supreme Value and the Source of all finite existence. Theism has usually thought of the Supreme Being as in some sense personal, or at least as One with whom personal relations were possible. This Supreme Being, in Anselm's phrase, id quo majus cogitari non potest, is, in the Theistic view, neither identical with the Universe nor wholly aloof and separate from it. The relation of God as Cause with the world has been conceived in various ways, the most common being creation, which itself may be capable of more than one interpretation. The idea of emanation, however, has also been employed, as in the Neo Platonic philosophy (chief exponent Plotinus, A.D. 204-2 70) which exercised a considerable influence upon Christian theology. The peculiarly Theistic doctrine of the relation of God with the world is often expressed by the phrase, "God is both transcendent and immanent."