**Info on Hinduism in general:
Hinduism is a collection of religions, instead of one religion. Hinduism(or Sanatana Dharma, real name) has four major sects Vaishnavism, Saivism, Shaktism, and Smartism. Vaishnavism(most common), the worship of Lord Vishnu, or his avatars, being the biggest. Vaishnavas worship God in the form of Avatars i.e. Vishnu, Rama, Krishna etc…All Vaishnavas subscibe to the belief in a personal God, having form, having shape, and incarnate as a human being. Avatars descend into human form during time of unrighteousness, moral decay, violence, and famine. In Hinduism Avatars are descibed in scripture and predicted. Vaishnavas also believe in Nirguna Brahman or attributeless Brahman(God without form). And all Hindus in general believe in reincarnation, karma, vegetarianism, dharma, ahimsa(non-violence) and accept the Vedas as revealed scripture.
Vaishnavism, (Vishnu worship[or any of the nine avatars]) majority in North India. Responsible for mainstream Hinduism. Bhagavat Gita, Srimad Bhagavatam, Mahabharata, Ramayana etc… In Vaishnavism there are dozens of sects Iskcon, BAPS Swaminarayan, Sri Vaishnava, Gaudiya Vaishnava being only some of many.
In general Hinduism considers God not just as the Supreme All-powerful Gigantic One, Who commands the humanity to tread the way He/She/It says, but also a personal God Whom the individual can worship out of love and not necessarily out of fear ! The fear brings one only upto certain point and beyond that it repels, but love takes through to the point. Devotion or bhakti as often referred to is a very key concept in Hinduism, even for the philosophically inclined ones. While the shashtras - be it vedas, Agamas, purANas - describe the Glory of God, one finds abundance of stotras that praise the God in love.
God is Formless or with Form ?
For Hindus God, as is, is beyond any attributes of form, color, shapes … That is, God does not have any specific form or name. In this state God is referred to as nirguNa brahman (attributeless god). However God takes forms as perceived by humans and this perceived form is called saguNa brahman (god with (good) attributes). These forms could range from calm to fierce to yogic (1). Each form has its significance. For example when one is depressed and sees the form of God Strong and Powerful, the seeker feels the moral boost that God would definitely be the support for the right thing. Similarly when in an auspicious ceremony would like the God to be the calm provider of boons. In a spiritually elevated state, the choice would be the yogic form of God. The forms provide a basis for the Hindu worshipper to easily pursue the otherwise incomprehensible Supreme. So Hinduism supports both form as well as formless worship of the God. Whether one worships in saguNa or nirguNa way, it is ultimately the same God. ***
Bhagavat Gita-Most Important Vedic Scripture
Hindus do not believe in Gods, in a plural sense. They believe in One Supreme God expressed in many forms. Hinduism is monotheistic! Vaishnavism, the largest Hindu denomination, subscribe to Vishnu as Supreme Brahman, and worship him alone. Also it is important to understand the difference between the Ultimate Supreme Godhead(Vishnu(in Avatar form)) or Brahman(formless God) and Devas. A Deva is the equivalent to an Angel in the Abrahamic tradition. Devas are subservient to the Supreme Lord Vishnu Brahman. Devas are gods, like Ganesha, Shiva, Durga, Indra, Hanuman etc… They are eternal servants to the Lord. But are not the Supreme Lord and Vedic scripture says that they shouldn’t be worshipped. But of course people do anyways. That’s why people view Hinduism as polytheistic. But Hinduism is purely Monotheistic at it’s core.
Devas in Classical Hinduism
History of Vaishnavism