Gautama Buddha is mentioned as an Avatar of Vishnu in the Puranic texts of Hinduism. In the Bhagavata Purana he is twenty fourth of twenty five avatars, prefiguring a forthcoming final incarnation. A number of Hindu traditions portray Buddha as the most recent of ten principal avatars, known as the Dashavatara (Ten Incarnations of God).
Siddhartha Gautama's teachings deny the authority of the Vedas and consequently [at least atheistic] Buddhism is generally viewed as a nāstika school (heterodox, literally "It is not so") from the perspective of orthodox Hinduism.
Many of the eighteen orthodox Puranas mention the Buddha in a less favouring light. They present the birth of the Buddha as a ploy by the Supreme God Vishnu to corrupt demons and sway them from Vedic teachings. Only by leading them astray with his teachings could the demons be destroyed. This belief is sometimes associated with the Asuras of Tripura (the three citadels) as well as others. Literature from the International Society for Krishna Consciousness, on the other hand, maintains that Krishna took the appearance of an atheistic teacher out of benevolence, in order to trick atheists into worshipping God (i.e., himself).
Buddha is mentioned as the 23rd avatar of Vishnu in the Chaubis Avtar, a composition in Dasam Granth traditionally and historically attributed to Guru Gobind Singh.
Some early Chinese Taoist-Buddhists thought the Buddha to be a reincarnation of Lao Tzu.
In Japan, since one of the symbols of Dainichi Nyorai (one of the non-historical buddhas of Mahayana Buddhism) was the sun, many equated Amaterasu, the Sun Goddess, with a previous reincarnation (bodhisattva) of Dainichi Nyorai.
Mirza Tahir Ahmad, the Fourth Caliph of the Ahmadiyya Community, in his book Revelation, Rationality, Knowledge & Truth, argues that Buddha was indeed a prophet of God who preached Monotheism. He quotes from the inscriptions on Ashoka's stupas which mention "Isa'na" which means God. He quotes, "'Thus spake Devanampiya Piyadasi: "Wherefore from this very hour, I have caused religious discourses to be preached, I have appointed religious observances that mankind, having listened thereto, shall be brought to follow in the right path, and give glory to God* (Is'ana)." The Ahmadiyya hold the view that the Buddha was indeed a Prophet of God.
In fact, a verse in the Qur'an quotes that God has sent many prophets to thee (Humanity). However, only a few have been named. It is believed by some[who?] that Buddha may (or may not) have been a Prophet of God sent to his people who taught Monotheism.
The Greek legend of "Barlaam and Ioasaph", sometimes mistakenly attributed to the 7th century John of Damascus but actually written by the Georgian monk Euthymius in the 11th century, was ultimately derived, through a variety of intermediate versions (Arabic and Georgian) from the life story of the Buddha. The king-turned-monk Ioasaph (Georgian Iodasaph, Arabic Yūdhasaf or Būdhasaf: Arabic "b" could become "y" by duplication of a dot in handwriting) ultimately derives his name from the Sanskrit Bodhisattva, the name used in Buddhist accounts for Gautama before he became a Buddha. Barlaam and Ioasaph were placed in the Greek Orthodox calendar of saints on 26 August, and in the West they were entered as "Barlaam and Josaphat" in the Roman Martyrology on the date of 27 November.
The story was translated into Hebrew in the 13th century by Abraham Ibn Chisdai (or Hasdai) as "ben-haMelekh v'haNazir" ("The Prince and the Nazirite").
^Smith, Peter (2000). "Manifestations of God". A concise encyclopedia of the Bahá'í Faith. Oxford: Oneworld Publications. p. 231. ISBN1-85168-184-1.
^Nagendra Kumar Singh (1997). "Buddha as depicted in the Purāṇas". Encyclopaedia of Hinduism, Volume 7. Anmol Publications PVT. LTD. pp. 260–275. ISBN978-81-7488-168-7.. List of Hindu scripture that declares Gautama Buddha as 9th Avatar of Vishnu is as follows
[Harivamsha (1.41) Vishnu Purana (3.18) Bhagavata Purana (1.3.24, 2.7.37, 11.4.23 Bhagavata Purana 1.3.24 Bhagavata Purana 1.3.24Archived 26 September 2007 at the Wayback Machine, Garuda Purana (1.1, 2.30.37, 3.15.26) Agni Purana (160.Narada Purana (2.72)Linga Purana (2.71) Padma Purana (3.252) etc. Bhagavata Purana, Canto 1, Chapter 3Archived 21 May 2013 at the Wayback Machine - SB 1.3.24: "Then, in the beginning of Kali-yuga, the Lord will appear as Lord Buddha, the son of Anjana, in the province of Gaya, just for the purpose of deluding those who are envious of the faithful theist." ... The Bhavishya Purana contains the following: "At this time, reminded of the Kali Age, the god Vishnu became born as Gautama, the Shakyamuni, and taught the Buddhist dharma for ten years. Then Shuddodana ruled for twenty years, and Shakyasimha for twenty. At the first stage of the Kali Age, the path of the Vedas was destroyed and all men became Buddhists. Those who sought refuge with Vishnu were deluded." Found in Wendy O'Flaherty, Origins of Evil in Hindu Mythology. University of California Press, 1976, page 203. Note also SB 1.3.28: "All of the above-mentioned incarnations [avatars] are either plenary portions or portions of the plenary portions of the Lord [Krishna or Vishnu]"
^"Buddhism". Islam International Publications. Retrieved 9 September 2010.
^Bhagavata Purana, Canto 1, Chapter 3Archived 21 May 2013 at the Wayback Machine - SB 1.3.24: "Then, in the beginning of Kali-yuga, the Lord will appear as Lord Buddha, the son of Anjana, in the province of Gaya, just for the purpose of deluding those who are envious of the faithful theist." ... SB 1.3.28: "All of the above-mentioned incarnations [avatars] are either plenary portions or portions of the plenary portions of the Lord [Krishna or Vishnu]"
^"in Sanskrit philosophical literature, 'āstika' means 'one who believes in the authority of the Vedas' or 'one who believes in life after death'. ('nāstika' means the opposite of these). The word is used here in the first sense." Satischandra Chatterjee and Dhirendramohan Datta. An Introduction to Indian Philosophy. Eighth Reprint Edition. (University of Calcutta: 1984). p. 5, footnote 1.
1 The list of ten avatars varies regionally. The two substitutions involve Balarama, Krishna and Buddha is considered the avatar of Vishnu. Krishna is almost always included; in exceptions, he is considered the source of all avatars.