For many, but not all Hindus their religion is monotheistic.( They believe in one God only.) They believe in one ultimate truth that encompasses all reality ( Brahman.) At first glance it seems hard to reconcile this belief with the Knowledge that there are said to be as many as 330,000,000 Hindu gods and demons. This apparent contradiction can be explained on the basis that they are all manifestations of Brahman, the creative force.
In early texts Brahman (the elemental creative spirit) was impersonal. It was not a god but something beyond god, it was ” the unproduced producer of all that exists.” No image of Brahman exists, as it has no form. It is an eternal presence.
Reference to Brahma (the masculine of the neuter Brahman), (a manifestation of Brahman) as the creator god, started to appear later. By the 4th /5th century AD Brahma was one of a trinity of gods (the three gods are known as the Trimurti), in one of the creation myths Brahma emerges from a lotus flower which Vishnu is holding whilst resting on the back of the cosmic serpent in the primeval waters. The Trimurti is represented by Brahma (the creator) Vishnu (the preserver) and Shiva (the destroyer). They comprise the three main physical representations of Brahman, who together are all powerful.
Brahma is the creator god. Images tend to show him with 4 heads and 4 arms. In these he holds a variety of objects. These usually include a drinking pot, a sceptre and the Vedas.
Vishnu is the preserver. He protects what is good in the world, and appears whenever evil threatens to overwhelm it. He is shown wearing a high crown and smiling. His symbols are the conch, the lotus, the club and the discus. He has already had 9 incarnations and is expected to have another on the final destruction of this world. His incarnations have taken animal and human form. As a human he was incarnated as Rama and Krishna (and also as the Buddha).
Shiva is the destroyer but as, in Hinduism, there can be no rebirth without death he is also the creator. Images show him with 1 or 5 faces, sometimes with a third eye and with 4 arms. These may hold his symbols of fire, a drum, a horn, and a trident or take up positions of action or protection. Often an arch of flame surrounds him (a common image is the dancing Shiva. He is also often represented by the lingam, a phallus.
A follower of Vishnu is a Vaishnavite and a follower of Shiva is a Shaivite. Numerically Vaishnavites form the largest sect.
The gods appear in different forms male, female, animal such as Ganesha the Elephant god. Other popular gods are Indra (god of rain), Chandra (moon god), Yama (god of death), Surya (sun god), Lakshmi (goddess of wealth), Hanuman (the devotee of Rama), Sarasvati (goddess of learning).
The gods are important as they are regarded as channels through which the godhead can work . They provide an opportunity for darshan. This means the sight of the god, but also the insight that can be obtained through worship.