Deities, holy beings.: Vishnu, Krishna
The root of the name Vishnu means "to pervade", and is a reference to a scripture in which he is said to descend down to earth in order to measure the extension of the world walking three steps, which symbolize the dawn, the zenith and the setting of the sun. In the most ancient core of the Veda Corpus, the sacred texts of Hinduism, he is not a central figure. Starting with later texts, such as the Brahmana (liturgical texts), he will progressively gain importance as the Ishvara (Supreme God, see below) whose duty is to preserve the cosmos.
He is a glorious and benevolent god, who descended to earth as Avatara (see below) in order to re-estabilish the corrupted cosmic order. One of its most famous and revered Avatara is Krishna, who is protagonist in one of the most important text of Hinduism, the Bhagavad Gita (see below).
Given his nature of benevolent and omnipresent Supreme God, his cult developed a way of worship typical of a large part of Hindu believers, the so called Bhakti (see below).
 

Main doctrinal tenets: the concept of Supreme God ( Ishvara)
Hinduism is commonly said to be a polytheistic religiosity, but it is better to understand it as Henotheism. Henoteism is the belief in and worship of a single god while accepting the existence or possible existence of other deities that may also be worshipped. In the case of Hinduism, a concept of pivotal importance is that of Ishvara (the Lord). This term is found in the epic of the Bhagavad Gita (see below) and identifies the Supreme God, who sustain the cosmos which is emanation of the Supreme God himself. The Supreme God is thus the personification of Brahman, the eternal ground of reality, which is behind a world in cyclical flux of birth, development and destruction. Because of this, Ishvara is different from the other deities, which, although being superior to men, are nonetheless subject to Samsara and Karman (the cycle of reincarnation and the law of deeds' retribution).
Hinduism could be called polytheistic in the sense that there are many, many different gods—classically there are said to be 330 million! But Hindus often worship a particular form of the god or goddess as the Supreme God, which is also called an Ishtadevata, a chosen or personal god. Some of these forms are pan-Indian, such as Vishnu or Shiva, while others are local, often only known at the regional level.

 

Main doctrinal tenets: the concept of descent of God on earth (Avatara)
Strictly connected with this idea of Ishvara is the concept of Avatara. This terms literally means "descent" and refers to the form the Supreme Deity assumes in order to manifest himself on earth to re-estabilish the collapsed cosmic order. Originally this doctrine was born in reference to the deity of Vishnu, and its main textual source is the Bhagavad Gita (see below). But soon other religious traditions who revere other gods as Supreme Deity appropriate this concept. Nowadays in India virtually every Supreme Deity has a list of Avataras which comprehend men, animal or lesser deities.

Main Doctrinal traditions: Bakthi devotion; Vishnuism
In Hinduism Bhakti refers to religious devotion in the form of active involvement of a devotee in worship of the divine. It is the love felt by the worshipper towards the personal God, Ishtadevata (see above). It rises to importance in the medieval history of Hinduism (500-1500 CE), where the Bhakti movement saw a rapid growth in Southern India.
Bhakti emphasises religious devotion and sentiment above ritual and orthopraxy. It is an integral aspect of Hindu culture and society in the modern era. The main text which promotes the Bhakti religiosity is again the Bhagavad Gita. It's not surprising therefore that one of the main Bhakti movements is Vishnuism, one of the major branches of Hinduism which is focused on the veneration of Vishnu. The Vishnu worshiper is expected to devote his/her entire life to the adoration of Vishnu, like the lover towards the beloved one. The aim of the Vishnu worship is to put him/herself completely in the hands of  god, who will save his devotee from the cycle of rebirth by mean of his grace.

Sacred texts and other main texts: the Bhagavad Gita
The Bhagavad Gita is a 700-verse scripture that is part of the larger Hindus epic Mahabharata. It is a sacred text of the Hindus. Theories on the date of composition vary considerably. Scholars accept dates from fifth century to second century BCE as the probable range.
The Bhagavad Gita is set in a narrative framework of a dialogue between prince Arjuna and his guide Lord Krishna, (see above). Facing the duty to kill his relatives, Arjuna is exhorted by his charioteer, Lord Kṛiṣhṇa, among others, to stop hesitating and fulfill his duty as a warrior and kill. Inserted in this appeal is a dialogue about methods and ideas concerning the attainment of liberation from the cycle of rebirth.
The Bhagavad Gita presents a synthesis of the concept of Dharma (the cosmic order), bhakti devotion, Avatara doctrine and ideals of liberation.

Contextualization and analysis of sources:
Source n° 1
Vishnu
This stele depicts the Hindus god Vishnu, attended by two consorts, Lakshmi (lower left) and Sarasvati (lower right).
Here Vishnu appears as a kingly god, standing erect on a lotus pedestal. Vishnu can be identified by the attributes he holds in his four hands. His two raised arms hold a mace or club and a lotus. His lower left hand hold a conch shell; his lower right hand hold a discus-like weapon.The four arms themselves are a typical attributes of Vishnu's omnipresence in the cosmos. When depicted with colors, his skin is always blue like the sky that encompass the whole world. As a kingly figure, Vishnu is adorned with an elaborate crown and jewelry. Some of his attributes are weapons of war. The conch shell is blown during battle.

Source n° 2
Bhagavad Gita chap. 4
In this excerpts Krishna, the guide of prince Arjuna, reveals himself as the Avatara of Vishu, understood in this text as the Supreme Deity. Vishnu explains that he manifests himself thanks to his Maya. The word Maya means unreal, illusory, or deceptive image of the creation. Due to the power of Maya one considers the universe as existent and distinct from Brahman, the Absolute which is beyond the world of constant change. Maya and Brahman are inseparable like fire and heat. In this context Brahman is understood as a personal deity who deliberately will descents on earth to restore the corrupted cosmic order, Adharma (Dharma plus privative alpha).

Source n° 3
Bhagavad Gita chap. 12
In this excerpts Arjuna asks Vishnu which practice (in the text: Yoga) is the best way to attain liberation from the cycle of incarnation. While the ascetic-style of worship of the impersonal, far and unmanifested Absolute, ( the Brahman) is still deemed as a way to reach liberation, it is a difficult path to choose (stanzas 3-5). Therefore, those devoted entirely to the worship of a personal deity, who reveal himself  (that is, the Bhaktas, those who perform Bhakti devotion) are nonetheless said to be "very holy" (stanza 2), and Vishnu will act towards them as a savior, rescuing them from the cycle of rebirth (stanza 7).
       

Intercultural & Interdisciplinary information.
Question 1) The term avatar is nowadays commonly used in computing. An avatar is the graphical representation of the user or the user's alter ego or character. It may take either a three-dimensional form, as in games or virtual worlds, or a two-dimensional form as an icon in Internet forums and other online communities. It is derived directly from the Sanskrit Avatara.
Question 2) It is important to bear in mind that Avatara does not mean incarnation of a god in human form. His essence remain fully divine, even though he doesn't seem so. Thus is different from the figure of Christ, who is at the same time Man and God. For many Indian Christian believers is difficult to accept the humanity of the figure of Christ, as it is difficult to conceive that a divine being could suffer and die.

Link to other module:
Christianity II. Themes, sec. 3