The concept of 33 koti devata in Hinduism!

The Hindu Cosmos

Classical Hinduism takes its form from the uniting of two different (and indeed opposing) worldviews. This unification is the result of a long religious and intellecutal confrontation (roughly 500 to 300 bce) between the Vedic Religion and the worldviews of Jainism and Buddhism. From the Vedic Religion, it took the life-affirming perspective ("life is good") and from Jainism and Buddhism, along with the late Upanishads it developed a life-negating view ("life is bad"). Both of these views were fit into the understanding of the cosmos that Hinduism developed out of the Vedas. To explain how this works, we must start with two intertwined descriptions of the cosmos, from which we will then move to the life-is-good and life-is-bad approaches to the human problem.

The Hindu Cosmos #1: The Real Estate and its Inhabitants.

A) The Vedic Gods

The sacrifices and rituals of the Vedas involve a number of gods and goddesses. There is Indra, for example, the warrior god who can be seen as the leader of the gods. With his band of Maruts, he defeated the demons of darkness each morning so that the sun could rise. The Vedic literature contains a number of stories about his exploits and successes. There is also the sky god Dyaus and a few goddesses, such as Aditi and Ushas.
Although the Vedas comprise the most sacred literature of Hinduism, the divine pantheon in them is essentially ignored in later Classical Hinduism. Only one god important in this period continue his significance later. This is Agni, who is both the god of fire, and the sacred fire itself. He continues to be worshipped in the daily rituals of each Hindu home. Every morning, an offering of clarified butter (ghee) and some grain cakes is shared communion-style between Agni (i.e., the fire) and the members of the household.

B) The Gods of Classical Hinduism

Hinduism has always had a remarkable ability to absorb new influences and ideas within its amorphous structure. This is true of the gods as well. One sage observed that there were 330 million divine beings in Hinduism. But if one looks for the most important gods, the usual answer is that there are three main gods, the "trinity" of Brahma, Vishnu, and Shiva. But this answer is unsatifactory, for Brahma--the emination of Brahman into the realm of maya--receives little regular worship. Indeed, if we determine the of importance of gods by the number of their temples, Brahma has almost none. Instead, a group of female gods appear much more important. So the following discussion will focus on Vishnu, Shiva, and the goddesses. Much of the information about these gods comes from the two epics of the Mahabharata and the Ramayana, as well as from the Puranas.
Vishnu is a mighty male god, who plays several roles for his followers. He is at once the creator of the cosmos, its sustainer, and its destroyer. His most common female consort is Lakshmi. (For a picture and description of Lakshimi, go here.) The followers of Vishnu are called Vaishnavites. On earth, he has appeared in the form of ten different avatars, i.e., forms or manifestations. Some of the avatars in which he appeared were animal, such as a fish or a boar. But the most common avatars are Krishna and Rama, forms in which he continues to be worshipped. (For a picture of some of Vishnu's avatars, go here and here.
There are three main stages in Krishna's worldly life. First, Krishna is born in a prison where his royal parents are being held by a rival king. His father works out a scheme to enable the baby Krishna to escape to a nearby village and replace him with another child. Krishna grows up as a mischevious boy within this village of cowherds, playing tricks on his family and friends.
Second, as a youth, Krishna woos all the gopis (female cowherds) in the village with his good looks, charms, and attentions. Although Radha is his favorite, he dallies with the other gopis as well. (For a picture of Krishna and Radha, go here or here or here.) Occasionally he even divides himself (makes copies, remember Multiplicity?) so that he can pay attention to several of the girls at once. These stories, while making good tales on the surface level, are also interpreted on a spiritual level. For an example of how this works, see this picture of Krishna and the gopis, along with its explanation.
Third, as an adult, Krishna regains his kingdom in northern India by killing King Kamsa, an act seen as the restoration of dharma. In the story of the Mahabharata, he then helps Arjuna (by serving as his chariot driver, [for a picture of Krishna and Arjuna drinking soma on the chariot, go here]) and his brothers (the Pandava brothers) in a war to regain their rightful kingdom. On the night before a major battle, Krishna and Arjuna have a long discussion about the nature of dharma and the cosmos, which is preserved within the Mahabharata as the Bhagavad Gita (for a picture of the discussion, go here). At the end of the discussion, Krishna reveals himself to Arjuna as Vishnu. The exploits of Krishna are told and rehearsed in the Vishnu temples and in the annual festival of the Ras Lila.
The other major avatar of Vishnu is Rama, the central figure of the Ramayana. In keeping with the actions in the story, Rama (i.e., Vishnu) bears the attributes of trust, faithfulness, and strength. Along with Sita, his faithful wife, Vishnu as Rama continues to be worshipped in temples and in the annual festival of the Ram Lila. (For a picture of Rama and Sita, go here.)
Shiva, by contrast, has no avatars, but he has a family of wives and children. Shiva was originally seen as the destroyer, but has since added the attributes of creator (destroy to make things anew), and sustainer. In fact, the figure of the dancing Shiva who sustains the world is a common Hindu image. Shiva's worshippers are known as Shaivites. The tales of exploits are mentioned in the Ramayana, but appear much more fully in the Puranas. Shiva's primary depiction is as a meditating sadhu, but due to the attentions of Parvati, one of his wives, he also has a familial side.
The main symbol of shiva is a lingam, a phallic shaped object. This symbol is placed as the central image in a Shaivite temple and often made from a valuable material, such as silver. It is usually two to three feet tall, and constitutes a focus of worship for his followers. For a picture of Shiva with a lingam (decorated as if in a temple) and explanation, click here (note: this picture takes a while to load). For a faster-loading picture of Shiva with Parvati, the child Ganesha, and a lingam, click here.
Shiva's "wives" are the symbols of feminine powers, called sakti. They are often worshipped within Shaivism, but can be worshipped on their own in a form of Hinduism called Saktiism. Although there are numerous female figures associated with Shiva, four stand out: Parvati, Umma, Durga, and Kali.
Parvati is the goddess of love and romance. She is young, beautiful and full of life. As such, she represents union with Shiva, a representation that has distinct sexual overtones. Indeed, they are often depicted in the act of intercourse, the combination of their male and female (sakti) energies sustaining the universe. (For a picture of Parvati, go here.) Parvati is also the mother of Ganesha (see below). Although Shiva intially tried to kill Ganesha, he ultimately adopted him and the three of them are a favorite family scene.
Umma is the wife who represents motherhood. She is seen as kind, caring, nurturing, and displaying other features of motherhood.
Durga represents the attribute of justice. She rides a tiger and carries the weapons of battle. In this character, she is unafraid to kill to reestablish justice. (Go here for a standard depiction of Durga.)
Kali is wild, terrible, and unpredictable, and is usually associated with death. She is usually depicted naked, wearing a necklace of human heads and a skirt of human arms. Blood drips from her sword. Death is thus connected with her activities. In fact, she is sometimes depicted dancing upon the prone form of Shiva, symbolizing the strength of wild and unpredictable power. The city of Calcutta (=Kali Ghat) is named after her. (For a picture of Kali, go here or here.)
Shiva also has two sons. The first, Ganesha, has the head of an elephant and is the god of overcoming obstacles, which links him to good luck and prosperity. ( Go here or here for a picture of Ganesha. For the stories about how Ganesha was created and how he got his elephant head, go here.) The second, Skanda, becomes the divine warrior and thus the god of war.


The Hindu Cosmos #2: What's really there?
Although Christianity holds that God is immanent (that is, everywhere throughout the universe), that is usually not meant in physical terms. God is near all humans (perhaps his spirit is in the air), but he is not in physical objects; God created, but he is not his creation. For example, he is not a chair nor is he in a chair.
Hinduism provides a radically different idea, one which goes against the evidences of human senses. The idea is quite simple: Brahman (the "creator" god) IS his creation. The cosmos is not so much a creation, but more an emanation from him. His essence lies in all created objects, including human beings. This means that the multiplicity of the cosmos--with all its gods, goddesses, humans, animals, and other beings and objects--is actually a unity; it is one divine being. The multiplicity that hides the cosmos' unity is called maya; that is the reality humans perceive with their senses everyday. The overcoming of maya to perceive true reality (Brahman) thus constitutes an important task in Hinduism.
This simple notion has a stunning ramification: the soul of each individual human being--called atman--IS Brahman. The soul of each person is thus Brahman, the entirety of creation. This is a difficult concept to comprehend, for how can the "small" soul of each person be identical with the "large" god of the cosmos? But it is the comprehension of this very idea that becomes a central goal in the panoply of human life and in the resolution of the human problem. [See below.]

The Human Problem and its Solution: The Life-Affirming View

For the part of Hinduism rooted in the Vedas that views life as good, the human problem is how to enjoy life, or, more precisely, how to enjoy one's lives. Since the samsara system continually causes people to be reborn after their deaths, every life should be lived to maximize one's enjoyment both in the present life and in future lives.
In terms of one's present life, enjoyment comes from working towards the first three goals of life: dharma (virtue), artha (success), and kama (pleasure). Success and pleasure clearly can bring about enjoyment in-and-of-themselves, but so can practicing virtue. But the real reward for following virtue, fulfilling the duties of one's varna and jati, one's stage in life, (etc.), comes in future lives. The more a person leads their life according to dharma, the greater a store of good karma they develop. Good karma of course leads to a higher position in rebirth, while bad karma can lead to a lower position, possibly even one below the human race (like a goat or a bug). The more virtuous a person is in in their present life, the higher they will be reborn in the next. And of course, the higher one is born, the more enjoyable life will be.

The Human Problem and its Solution: The Life-Negating View

The part of Hinduism that views life as bad defines the human problem in a different way. Since life is not a good experience, many lives are definitely not pleasant. The problem therefore is how to stop living. A person could kill themselves of course, but that would only cause a rebirth. The problem is obviously how to get out of the system of samsara, how to die without being reborn.
The solution is to gain moksha, namely, release. The simple characterization of this goal is for a person to realize the true nature of the cosmos. That is, they must come to the understanding, with every fiber of their being, that atman and Brahman are one and the same. The key is to realize this with "every fiber of their being"; head knowledge does not count.
The more complex characterization of this goal is actually a fuller version of the previous one. First, recall that each person is reborn on the basis of their karma: good karma enables a higher birth, while bad karma results in a lower birth. But what if there is no karma at all? In this situation, there would be nothing attached to the individual that could determine where they would be reborn. This, in turn, would prevent rebirth and thus take the person out of the system.
But how does one avoid having karma? How does one come to realize that atman is Brahman with their whole being? This comes about through the practice of one of several different forms of yoga, which are discussed on the Hindu Religious Life page.