AGNOSTICISM is the view that the existence of God cannot be known since it cannot be proven. It falls between the theist and the atheist {see below}. The agnostic claims ignorance
ATHEISM is the denial of the existence of God or gods
DEISM originally meant believing in the existence of a God or gods; today it is generally defined as a belief in the existence of a supreme being who is the ground and source of reality but who does not intervene or take an active interest in the natural and historic order.
HUMANISM is the nontheistic, rationalist movement that holds that man is capable of self-fulfillment, ethical conduct, etc. without recourse to a divine force controlling nature or the universe.*
PANTHEISM is the belief that God and the universe are ultimately identical. It may equate the world with God or deny the reality of the world, maintaining that only the divine is real and that sensory experience is illusory. It is a characteristic feature of Hinduism and certain sects of Buddhism.
RATIONALISM is the acceptance of reason as the only authority in determining actions and opinions.*
THEISM is the belief in a single divine being who is transcendent and personal, who created the world and who, although involved with and related to the creation, is distinct from it. The creator is portrayed as intelligent, powerful and moral. Theism is a feature in faiths such as Judaism, Islam and Christianity.
The above definitions, except those marked with a (*), are quotes from the 1994 edition of the Larousse Dictionary of Beliefs and Religions, edited by Rosemary Goring. Those marked with a (*) are quotes from the Third College Edition of Webster's Dictionary edited by Victoria Neufeldt.