To elaborate a little more –
It’s not easy to get a grasp of what Hinduism is and how it works without spending a lot of time with different kinds of Hindus. It’s really a case of the more you know, the more you know how little you know. Get to know one Hindu family well and you’ll get a good idea of what Hinduism is from their perspective, but I would caution you not to accept much of that knowledge as universally applying to Hindus generally.
Hinduism has no source of ultimate authority, no universally accepted Torah, Bible, or Koran. Hinduism has no founder or universally accepted prophet, no Abraham, no Moses, no Jesus, no Mohammed. Hinduism has no universally accepted baseline of beliefs or dogma or practices. Hinduism has no borders.
I’ll tell you some widely accepted, but not even then universal, baselines. A Hindu is born, not made. A Hindu doesn’t stop becoming a Hindu by practicing other religions.
Hinduism has at least three categories of gods – Vedic (Indra, Yama, Agni, Rudra, Vayu, Varuna, etc.), Hindu (Brahma, Vishnu, Shiva, Durga, Sarasvati, Lakshmi, Ganesh, Karttik, etc.), “local” gods (Murugan, Venkateshwara, Nataraja, Jaggannath, Sheetal, Ganapati, etc.).
It’s not even clear to what extent these gods are separate entities or personalities. Are Durga, Parvati, Sarasvati, Lakshmi, and Kali separate goddesses or are they all just different aspects of the Goddess (Devi). If the latter, how can it be that Sarasvati and Lakshmi are the daughters of Parvati (sometimes Durga). Are Parvati and Durga the same goddess or different? Are Durga and Kali the same goddess or different? If the latter, how do Durga and Kali both go into battle together against the forces of Chaos?
Hinduism has at least three “trinities” – Brahma-Vishnu-Maheshvar (Shiva), Shiva-Vishnu-Devi, Sarasvati-Lakshmi-Parvati.
The “local” gods are almost always identified with one member of the Shiva-Vishnu-Devi trinity. Thus, is Venkateshvara simply a “form” of Vishnu? Well, really, he was a completely independent mythological figure who much later got classified as “a Vishnu god.”
Are Krishna and Rama merely “avatars” of Vishnu? Or are they gods on their own, worthy of individual worship? Is Hanuman merely a monkey, a monkey-man companion of Rama or is he a god worthy of worship on his own? Are Rama and Sita together separate entities or are they merely Vishnu and Lakshmi? (And what about Sita’s husband?)
Lakshmi is Vishnu’s consort and Parvati is Shiva’s consort … but, wait, aren’t Parvati and Lakshmi both Devi? … but, wait, isn’t Lakshmi the daughter of Parvati/Durga? But, wait, isn’t Kali Shiva’s consort?
Which are the true Hindus? Shaivites (Shiva worshippers), Vaishnavites (Vishnu/Krishna/Rama-Sita worshippers), Shakti-ites (Goddess worshippers), and Smart-ites (who believe in a universal Brahman). Vaishnavites believe in vegetarianism. Shaivites and Shakti-ites believe in blood sacrifice. Many Hindus claim to be more than one of these.
Hinduism really isn’t a single religion. It’s an amalgamation of many sets of beliefs – the Vedic religion of the Aryans, who worshipped Indra, the sky/warror/king, very much like Zeus or Jehovah – the Sanatana Dharma of the pre-Aryan peoples, who believed in an all-encompassing Brahman – later Hindu mythologies of Shiva, Vishnu, and company – absorbed “local” gods and religions who were often assimiliated or co-opted by identification with a major Hindu god – “reform” movements, like Buddhism, Jainism, and Sikhism – modern reformers, like Ramakrishna or Vivekananda, who tried to make Hinduism more westernized (“See, it’s not really polytheism!”) – ongoing personality cults (Hare Krishnas, Sai Baba, etc.).
Does Vishnu have four arms? Is Hinduism really polytheistic or is apparent polytheism merely a metaphor operating in underlying monotheism or universalism? Every Hindu will give you a different answer. A Hindu seeking to gain acceptance for Hinduism in a Western culture will very likely go the “it’s not really polytheism” route. However, the majority of Hindus, living in India, with little contact with western ideas or highfalutin’ theology believe and behave as if multiple arms and polytheism are literally true. Which one is right? Well, both.
Were Krishna and Sita lovers? Well, there’s a test that describes in exquisite detail how much fun Krishna had with his penis, not only with Sita (married to another man, I remind you), but with all the local milkmaids. Then again, someone told me with a straight face that all that sex-talk was merely metaphorical, and Sita and all those milkmaids loved Krishna only spiritually.
I, like 'Mika, would be happy to entertain further questions. And I’d welcome them in this thread, just so you can see how everyone will give you different answers to all your questions.