Monotheism is a theory which belief in the existence of one deity or in the single existence of God. Monotheism in Hinduism is known as "Ekanyana" and God Almighty is Ekam, the one.

According to a saying of a scholar in Hinduism there are both monism and monotheism. It is confusing to call the Abrahamic religions the monotheistic traditions meaning that monotheism is absent from the Eastern traditions. Vedanta philosophy includes many monotheistic schools. The schools accept in the existence of multitude of gods and goddesses, but strongly stresses in the supremacy of the ultimate Deity.

The Smartas among the Hindus believe in God or the Almighty having three features as Brahma, Vishnu and Shiva. They are together called, the Trimurti or the Hindu trinity. These three different Trinity are part of one and the same God. The Four major sects of modern Hinduism, Vaishnavism, Shaivism, Shaktism, and Smartism, all believe in one God but differ in their conceptions.

The two main forms of differences are between the two monotheistic denominations of Vaishnavism, which considers God as Vishnu, and Shaivism, which conceives God as Shiva. Other aspects of God are in fact aspects of Vishnu or Shiva. The Smartas follow the philosophy of Advaita philosophy, are the monists. The monists` belief in the several manifestations of the one god who is the source of being. Like a single beam of light separated into colours by a prism, Hindu monists spots one unity, with the personal gods, different aspects of only one Supreme Being and are valid to worship. Other Smarta aspects of God include Devi, Vishnu, Ganesh, and Shiva.

It is the Smarta view that dominates the view of Hinduism in the West. By contrast with Smarta/Advaita belief, Vaishnavism and Shaivism follow a singular concept of God, or panentheistic monotheism or panentheistic monism. A Smarta following the Advaita tradition can select their "Ishta-deva", that is God that one prays to most. The Vaishnavism on the other hand do not belief in this, they stresses in the worship on one aspect of Vishnu that is Rama.

The Vedas, Upanishads and the Bhagavata Gita say that there is only one God and God is described as the Eternal Truth. God is birthless, ageless, and omnipresent. He is all pervading. Many scholars interpret the verses as either Monotheistic and Pantheistic or a combination of both.

Hindus also believe that God has six attributes but nevertheless the actual number of auspicious qualities of God, are immeasurable. The first of the Attribute is Jnana or the Omniscience, which is defined as the power to know about all beings simultaneously. Second is the Aishvarya derived from the word Iswara, also means Sovereignty, which consists in unchallenged rule. Third is Shakti, the Energy, or power, which is the capacity to make the impossible possible. The fourth attribute is the Bala or Strength which is the capacity to support everything by will and without any fatigue. The fifth attributes deals with Virya or valour, which indicates the power to retain immateriality as the Supreme Being in spite of being the material cause of mutable creations. The last one of the attribute is the Tejas or Splendor which expresses his self-sufficiency and the capacity to overpower everything by his spiritual effulgence.

Alternatively the Nyaya School of philosophy in Hinduism has made several opinions regarding a monotheistic view. The Naiyanikas have given an argument that a God can only be one. In the Nyaya Kusumanjali, this is discussed against the proposal of the Mimamsa School that said that there were many demigods or Devas and sages or Rishis in the beginning, who wrote the Vedas and created the world. Thus Nyaya School of philosophy says that the polytheists have given the existence and origin of his several celestial spirits but none of them are be rational. Therefore it is derived that it is logical to assume that there is only one and sole eternal God who is omniscient.