Theism is the belief in the existence of one or more divinities or deities (gods), which are both immanent (i.e. they exist within the universe) and yet transcendent (i.e. they surpass, or are independent of, physical existence). These gods also in some way interact with the universe (unlike in Deism), and are often considered to be omniscient, omnipotent and omnipresent.
The word "theism" was first coined in English in the 17th Century to contrast with the earlier term Atheism. "Deism" and "theism" changed meanings slightly around 1700, due to the increasing influence of Atheism: "deism" was originally used as a synonym for today's "theism", but came to denote a separate philosophical doctrine (see Deism).
Theism incorporates Monotheism (belief in one God), Polytheism (belief in many gods) and Deism (belief in one or more gods who do not intervene in the world), as well as Pantheism (belief that God and the universe are the same thing), Panentheism (belief that God is everywhere in the universe but still greater and above the universe) and many other variants (see the section on Philosophy of Religion). What it does not include is Atheism (belief that there are no gods) and Agnosticism (belief that it is unknown whether gods exist or not).
The Abrahamic faiths (Judaism, Christianity and Islam) as well as Hinduism, Sikhism, Baha'i and Zoroastrianism, are all theistic religions.