Indian literature comprises everything which is included in the word 'literature' in the broadest sense of the term: religious and mundane, epic and lyric, dramatic and didactic poetry, as well as narrative and scientific prose. However forefront can be found religious literature and religious influence in Indian literature, beginning from the Vedic Period. Not only the Brahmins in their Veda and the Buddhists in their Tipitaka, but also, numerous religious sects that have appeared in India have on record plenty of literary works - hymns, sacrificial songs, magic songs, myths and legends, sermons, theological treatises and polemic writings, text books of rituals and of religious order. In this literature, is found heaped up material of inestimable value, which cannot be overlooked by any scholar of religion. In addition to activity in the field of influence of religion in Indian literature, which had begun thousands of years ago and being continued even till the present day, there have been in India even in ancient times songs of heroes which in the course of centuries got condensed into two great popular epics - the Mahabharata and the Ramayana. These sagas were the sources, which had supplied material for centuries to the poets of India in the Middle Ages and works of epic poetry were thus born which are termed artistic epics in contrast to those popular epics.
The aspect can never be ignored that all sorts of religious influence of Indian literature begins and literally ends in Sanskrit literature. It was Sanskrit literature and its umpteen divisions from pre-Vedic age, Vedic Sanskrit, Epic Sanskrit and Classical Sanskrit literature, which had virtually circularised all the kinds of religious aspects which could have been held from such ancient times. However, it needs to be noted that Sanskrit literature was an out and out Hindu attempt, with Brahmin rishis and learned men or sages trying to propagate religious doctrines or theories through word of mouth or penning scriptural masterpieces. The branching out of religious influence upon Indian literature into the likes of Buddhism or Jainism is a much later concept, let alone Islamic religious authority into medieval times. However, whatever might have been the case of Sanskrit, it was never for once asserted a fact that spiritual or religious bigotry or forceful and wishful thinking and fantastic impressions were created upon the minds of men; the very real and valid facts had been passed around with Almightiest as the mouthpieces. Be it in the sphere of poetry, prose, drama or short story, Sanskrit literature has done it all. The basic religious influential texts of Sanskrit in India literature would comprise - the four Vedas (Rig Veda, Yajur Veda, Sama Veda and Atharva Veda); each of these Vedas is again divided into four parts - Samhitas (the principal text containing the mantras), Brahmanas (their application to religious rituals), Aranyakas (portions intended for deep meditation and for those residing in forests) and lastly, the Upanishads. The Upanishads form the concluding part of Vedic literature and are referred to as the Vedanta - the quintessence of Vedic thought, vision and wisdom. They are also referred as Veda Sirsha, the top-ranking text in Vedic lore. The Muktika Upanishad enlists 108 Upanishads, of which Adi Sankara had commented on eleven - Isha, Kena, Katha, Prasna, Mundaka, Mandukya, Taittiriva, Aitereya, Chandogya, Brihadaranyaka and Narisimhapurvatapini. The Puranas, which are dated later than the two great Epics, are the epic legends comprising five main topics: Sarga (creation), Pratisarga (dissolution and recreation), vamsa (divine genealogies), manvantara (ages of Manu) and vamsanucarita (dynastic history).
The Indian Puranas, next in line to the brilliantly upholding religious influence upon Indian ancient literature, comprise 18 in number viz., Brahma, Padma, Visnu, Vayu, Bhagavata, Naradiya, Markandeya, Agni, Bhavisya, Brahma-vaivarta, Varaha, Linga, Skanda, Vamana, Kurma, Matsya, Garuda and the Brahmanda Puranas. The Manu Smriti(or Barghu Samhita), belonging to 1st century B.C., is the best illustrator of the Dharma-sastras or Smritis or the Hindu religious laws, which do loftily try to contour the routes that religion had played during Vedic times in Indian literature. Manu Smriti consists of twelve chapters, five of which are committed to rules of conduct for individuals belonging to different varnas and asramas. The other important Smritis include Yajnavalkya Smriti (4-5th century A.D.), Katyayana Smriti-saroddhara, Brahaspati Smriti and the Narada Smriti.
The next important group of religious texts in Sanskrit are the Agama Sastras or the Tantric texts, which are subdivided into three categories, incorporating - the Agamas, the Samhitas and the Tantras, which relates to the Shaiva, the Vaishnava and the Shakta sects respectively. Stotra literature is also an important form of ancient religious Sanskrit literature. It consists of hymns addressed to Shiva, Vishnu, Shakti, Surya and Ganapati. Some of the instances would include: Bana's Chandi-sataka, Mayura's Surya-sataka, Shankaracharya's Ananda-lahari, Saundarya-lahari and Carpata-panjari, Muka's Pancasati, Pushpadanta's Sivamahimmah-stotra, Anardavardhana's Devi-sataka, Bhatta Naryanan's Stava-cintamani and Kulasekhara's Mukunda-mala.
By this time, it can already be apprehended that religion has long had exercised a strong influence on Indian literary writing. However, as any Indian would be aware in present times, not every religion was however predominating; the principal religions of the country have been Hinduism, Buddhism, Jainism, and of course, Islam. As such, religious influence on Indian literature cannot just be ignored and stacked away in the haystack. Throughout the history of Indian literature, particular religious doctrines have constituted common threads. One such doctrine is karma - the chain of good and bad actions and their inevitable and predestined outcomes, which result in the reiterated birth and death of the human body. The mythology of the prevailing Hindu religion has time and again portrayed the deities Vishnu, Shiva, the Goddess (Devi) and others. This mythology further has influenced Indian literary texts, from ancient epics in the Sanskrit language to medieval poems in umpteen various languages of different regions, to modern works in Indian English. The emergence of the popular religions Buddhism and Jainism during the 6th century B.C., had given rise to literature in Pali and in the several dialects of Sanskrit acknowledged as Prakrit (meaning "natural language"). Meanwhile, Tamil, a Dravidian language, had emerged as the most important language in the south. A recorded literature in Tamil dates from the 1st century A.D. Rich literary traditions have emerged in Tamil, Telugu, Kannada, and Malayalam - all of which represent modern languages that had developed from Old Tamil and its dialects. True, religious influences in Indian literature had virtually been successful to lap up every language that it could lay its hands on, which commonly was not an unachievable task, with such a religious-minded Indian populace.
Placing aside Hinduism, Jainism and Buddhism have also been considerably victorious to have exerted a tremendous religious influence upon Indian literature, beginning from the 6th century. Amongst the Jains, the earliest work in Sanskrit was thoroughly dedicated to religious writing is Umasvamin's Tattvarthadhigama-Sutra, which epitomises the whole Jain creed in approximately 375 sutras coiffed in ten chapters. There have existed several commentaries penned on this work in Sanskrit, which includes Pujyapada's Sarvartha-siddhi-vrtti (6th century), Akalanka's Tattvartha-raja-varttika (8th century) and Vidyanandin's Tattvartha-sloka-varttika (9th century). The other important Jain texts in Sanskrit incorporate - Subhachandra's Jnanarvana and Hemachandra's Yogasastra, Ravisena's Padmacharita (7th century), Jinasena's Harivamsa Purana (8th century) and Mahapurana of Jinasena and Gunabhadra (9th century). Harisena's Katha kosa (10th century) is the most superlative illustration of Jain short stories in Sanskrit. Hymns and Jain lyrical poetry is best depicted by Bhaktambara-stotra of Manatunga, Kalyana-mandira-stotra of Vadiraja, Visapahara-stotra of Dhananjaya and Jina-chaturvimsatika of Bhupala. Hence, it is mostly understood that Jain influence on Indian literature has been most profound and vast, to have incorporated such massive Sanskrit versions by legends.
Buddhist influence on Indian literature, most manifest under Gautama Buddha, however, does not only begin and end in this enlightened man, but stretches to other venerated disciples after his Mahaparinirvana (the death of Gautama Buddha). From amongst the Buddhist texts, the Mahavastu is one of the most crucial works, belonging to the Hinayana School of Buddhism. It is an encyclopedia of Buddhist legends and doctrines. Buddhist texts in Sanskrit were enriched and lend a special lexicon by great writers like Asvaghosa, Nagarjuna, Aryadeva, Asanga, Vasubandhu, Dinnaga, Vasumitra, Dharmapala, Dharmakirti, Santideva and Santaraksita. Buddhacharita and Saundarananda are the two masterpieces of the historic Asvaghosa. Sariputra-prakarma - a drama in nine acts, is the oldest dramatic work extant in Sanskrit literature, yet again strongly accentuating on the fact religious influence on Indian literature could never be ignored, providing a secured base for times of today. The other great Buddhist texts in Sanskrit are Nagarjuna's Madhyamika-karika and Mahdyamika-sastra, Aryadeva's Catuhsataka, Asanga's Yogacara-bhumi-sastra, Vasubandhu's Vimsika and Trimsika, Dinnaga's Nyayapravesa, Dharmakriti's Nyayabindu, Shantideva's Siksa-sammucchaya and Santaraksita's Tattva-sangraha.
Coming down to few centuries down the line towards advancement of time, religious influence on Indian literature besides the amalgamated effort of the mentioned religions, also was most profound in a very different direction. By the termination of the earliest period of the beginning of the first centuries A.D., the 13th and 15th centuries were most crucial with regards to the emergence and spread of the 'Bhakti' cult. With every possible Indian religion coming under the charm and sway of this Bhakti preaching that had turned into a movement, various religious thinkers and literary personalities had sprung forth. The Bhakti Movement during the 13th to 15th centuries, had been captivating and was indeed like a catalyst, which was victorious to attract the common mass towards literature for the first time, as it was penned not all in Sanskrit - regarded the language of the elite and the high-classed. With men like Kabir, Chaitanya, Surdas, Meera Bai, Tulsidas, Ravidas, Namdeo, or Tukaram, including several other masters - Indian Bhakti literature in every domain of poetry, lyrical verses, drama, or just simple doctrines of philosophical thoughts, had been profound too resounding to have made the populace believe in One God. Hence, the Bhakti influence in Indian literature seems to have been accepted by some, yet again, being rejected by another lot; whatever, might have been the state of affairs back then, Bhakti cult could not be ignored in medieval Indian history, which later had paved the path to be more smoothened for the ushering in of Islamic overwhelm, which for a huge period of time, completely had eclipsed Hinduism.