In monotheism and henotheism, God is conceived as the Supreme Being and principal object of faith. The concept of God as described by theologians commonly includes the attributes of omniscience, omnipotence, omnipresence, omnibenevolence, divine simplicity, and eternal and necessary existence. In theism, God is the creator and sustainer of the universe, while in deism, God is the creator, but not the sustainer, of the universe. Monotheism is the belief in the existence of one God or in the oneness of God. In pantheism, God is the universe itself. In atheism, God is purported not to exist, while deemed unknown or unknowable within the context of agnosticism. God has also been conceived as being incorporeal, a personal being, the source of all moral obligation, and the "greatest conceivable existent". Many notable medieval philosophers and modern philosophers have developed arguments for and against the existence of God. There are many names for God, and different names are attached to different cultural ideas about God's identity and attributes.