Although analogies have been drawn between Buddhism and Christianity, there are differences between the two religions beginning with monotheism's place at the core of Christianity, and Buddhism's orientation towards non-theism (the lack of relevancy of the existence of a creator deity) which runs counter to teachings about God in Christianity; and extending to the importance of grace in Christianity against the rejection of interference with karma in Theravada Buddhism, etc. Another difference between the two traditions is the Christian belief in the centrality of the crucifixion of Jesus as a single event believed to act as the atonement of sins and its direct contrast to Buddhist teachings.
Though some early Christians were aware of Buddhism which was practiced in both the Greek and Roman Empires in the pre-Christian period, the majority of modern Christian scholarship has roundly rejected any historical basis for the travels of Jesus to India or Tibet or direct influences between the teachings of Christianity in the West and Buddhism; and has seen the attempts at parallel symbolism as cases of parallelomania which exaggerate resemblances. However, in the East syncretism between Nestorian Christianity and Buddhism was widespread along the Silk Road in Antiquity and the Middle Ages, and was especially pronounced in the medieval Church of the East in China, as evidenced by the Jesus Sutras.
The origins of Christianity go back to Roman Judea in the early first century. The four canonical gospels date from around 70–90 AD, the Pauline epistles having been written before them around 50–60 AD. By the early second century, post-apostolic Christian theology had taken shape, in the works of authors such as Irenaeus, although Christianity is seen as the fulfillment of Jewish prophecy regarding the "Messiah" which dates back much further.
Starting in the 1930s, authors such as Will Durant suggested that Greco-Buddhist representatives of Emperor Ashoka who traveled to Syria, Egypt and Greece may have helped prepare the ground for Christian teaching. Buddhism was prominent in the eastern Greek world (Greco-Buddhism) and became the official religion of the eastern Greek successor kingdoms to Alexander the Great's empire (Greco-Bactrian Kingdom (250 BC – 125 BC) and Indo-Greek Kingdom (180 BC – 10 CE)). Several prominent Greek Buddhist missionaries are known (Mahadharmaraksita and Dharmaraksita) and the Indo-Greek king Menander I converted to Buddhism, and is regarded as one of the great patrons of Buddhism. (See Milinda Panha.) Some modern historians have suggested that the pre-Christian monastic order in Egypt of the Therapeutae is possibly a deformation of the Pāli word "Theravāda", a form of Buddhism, and the movement may have "almost entirely drawn (its) inspiration from the teaching and practices of Buddhist asceticism". They may even have been descendants of Asoka's emissaries to the West.
Buddhist gravestones from the Ptolemaic period have been found in Alexandria in Egypt decorated with depictions of the dharma wheel, showing that the Buddhists were living in Hellenistic Egypt at the time Christianity began. The presence of Buddhists in Alexandria has led one author to note: "It was later in this very place that some of the most active centers of Christianity were established." Nevertheless, modern Christian scholars generally hold that there is no direct evidence of any influence of Buddhism on Christianity, and several scholarly theological works do not support these suggestions. However, some historians such as Jerry H. Bentley suggest that there is a real possibility that Buddhism influenced the early development of Christianity.
It is known that prominent early Christians were aware of Buddha and some Buddhist stories. Saint Jerome (4th century CE) mentions the birth of the Buddha, who he says "was born from the side of a virgin"; it has been suggested that this virgin birth legend of Buddhism influenced Christianity. The early church father Clement of Alexandria (died 215 AD) was also aware of Buddha, writing in his Stromata (Bk I, Ch XV): "The Indian gymnosophists are also in the number, and the other barbarian philosophers. And of these there are two classes, some of them called Sarmanæ and others Brahmins. And those of the Sarmanæ who are called 'Hylobii' neither inhabit cities, nor have roofs over them, but are clothed in the bark of trees, feed on nuts, and drink water in their hands. Like those called Encratites in the present day, they know not marriage nor begetting of children. Some, too, of the Indians obey the precepts of Buddha (Βούττα) whom, on account of his extraordinary sanctity, they have raised to divine honours."
In the Middle Ages there was no trace of Buddhism in the West. In the 13th century, international travelers, such as Giovanni de Piano Carpini and William of Ruysbroeck, sent back reports of Buddhism to the West and noted some similarities with Nestorian Christian communities. Indeed, syncretism in the East between Nestorian Christianity and Buddhism existed along the Silk Road throughout Antiquity and the Middle Ages, and was especially pronounced in the medieval Church of the East in China, as evidenced by the Jesus Sutras.
When European Christians made more direct contact with Buddhism in the early 16th century, Catholic missionaries such as St. Francis Xavier sent back accounts of Buddhist practices. With the arrival of Sanskrit studies in European universities in the late 18th century, and the subsequent availability of Buddhist texts, a discussion began of a proper encounter with Buddhism. In time, Buddhism gathered followers and at the end of the 19th century the first Westerners (e.g. Sir Edwin Arnold and Henry Olcott) converted to Buddhism, and in the beginning of the 20th century the first westerners (e.g. Ananda Metteyya and Nyanatiloka) entered the Buddhist monastic life.
In the 19th century, some scholars began to perceive similarities between Buddhist and Christian practices, e.g. in 1878 T.W. Rhys Davids wrote that the earliest missionaries to Tibet observed that similarities have been seen since the first known contact. In 1880 Ernest De Bunsen made similar observations in that with the exception of the death of Jesus on the cross, and of the Christian doctrine of atonement, the most ancient Buddhist records had similarities with the Christian traditions.
Late in the 20th century, historian Jerry H. Bentley also wrote of similarities and stated that it is possible "that Buddhism influenced the early development of Christianity" and suggested "attention to many parallels concerning the births, lives, doctrines, and deaths of the Buddha and Jesus". Some high level Buddhists have drawn analogies between Jesus and Buddhism, e.g. in 2001 the Dalai Lama stated that "Jesus Christ also lived previous lives", and added that "So, you see, he reached a high state, either as a Bodhisattva, or an enlightened person, through Buddhist practice or something like that." Thich Nhat Hanh affirmed core Christian beliefs such as the trinity, and the death and resurrection of Jesus Christ, in his book Living Buddha, Living Christ. Bokin Kim, similarly, sees Christ as the Buddha Dharmakaya, and Jesus as similar to Gautama who was just a historical manifestation of the transhistorical Buddha.
There are inherent and fundamental differences between Buddhism and Christianity, one significant element being that while Christianity is at its core monotheistic and relies on a God as a Creator, Buddhism is generally non-theistic and rejects the notion of a Creator God which provides divine values for the world.
The Nicene Creed, currently the most widely used Christian creed, states that "We believe in one God, the Father Almighty, Maker of heaven and earth, and of all things visible and invisible". However, the notion of theistic creation is generally foreign to Buddhist thought, and the question of the existence of God is perhaps one of the most fundamental barriers between the teachings of Christianity and Buddhism. Although Mahayana Buddhism expresses belief in the saint-like state of a Bodhisattva this is very different from the notion of Creator God in Christianity. While some variations of Buddhism believe in an impersonal eternal Buddha or trikaya, in general Buddhism sees empty space as eternal and without a starting point of creation. According to the Dalai Lama, belief in a Creator could be associated with the understanding of emptiness.
According to the Oxford Handbook of Eschatology, there are inherent differences in the Christian and Buddhist beliefs regarding the End Times and eschatology. Jan Nattier states that while Buddhism has a notion of "relative eschatology" that refers to specific cycles of life, the term "Buddhist eschatology" does not relate to any "final things", or that the world will end one day – Buddhist scripture routinely referring to the "beginningless Saṃsāra" as a never ending cycle of birth and death with no starting point. However, Christian eschatology directly involves the concept of "end to all creation" at the Last Judgement when the world will reach its conclusion.
There are other fundamental incompatibilities, e.g. while grace is part of the very fabric of Christian theology, in Theravada Buddhism no deity can interfere with karma, and hence the notion of any type of grace is inadmissible within these teachings. Mahayana Buddhism however, differs on this issue.
The crucifixion of Jesus as a single event in history that acts for the atonement of sins is a central element of Christian belief. This, however, produces a strong difference between Christian and Buddhist teachings. Buddhist scholar Masao Abe pointed out that while "the event of the Cross" is central to Christianity, it is not possible for Buddhism to accept its importance. Buddhist philosopher D. T. Suzuki stated that every time he saw a crucifixion scene it reminded him of the "gap that lies deep" between Christianity and Buddhism.
Suggestions have been made that Buddhism may have influenced early Christianity. Buddhist missionaries, sent by Emperor Ashoka to India, Ceylon, Syria, Egypt and Greece, may have helped prepare for the ethics of Christ. Gnostics (a small number of sects) are not considered part of mainstream Christianity and some have been declared heretical. However, Elaine Pagels proposes Buddhist influences on Gnosticism. Pagels suggested that there are parallels with teachings attributed to Jesus Christ and teachings found in Eastern traditions, but concludes that these parallels might be coincidental, since parallel traditions may emerge in different cultures without direct influence. Buddhist Jack McQuire has suggested that in the 4th century, Christian monasticism developed in Egypt, and it emerged with a corresponding structure comparable to the Buddhist monasticism of its time and place.
The suggestion that an adult Jesus traveled to India and was influenced by Buddhism before starting his ministry in Galilee was first made by Nicolas Notovitch in 1894 in the book The Unknown Life of Jesus Christ which was widely disseminated and became the basis of other theories. Notovitch's theory was controversial from the beginning and was widely criticized. Once his story had been re-examined by historians, Notovitch confessed to having fabricated the evidence.
A number of scholars have stated that suggestions of an influence from Buddhism on Christianity, particularly Jesus's alleged travels to Buddhist India, are fanciful and without any historical basis:
Christian influence on Buddhism in the 18th and 19th centuries was primarily by example of modern forms of religious education. During the last centuries, Christian missionaries have influenced many Buddhist groups such as the Buddhist nun Cheng Yen who, after being inspired by the humanitarian aid done by Catholic nuns, decided that Buddhists need "to do more than simply encourage the private cultivation of people's souls". Her works eventually led to the foundation of Tzu Chi, a non-profit humanitarian group in Asia.
Buddhism has been gaining popularity in the west. Starting with a cultural and academic elite in the 19th century, it is now widespread in western culture, especially since the 1960s.
In the 20th century Christian monastics such as Thomas Merton, Wayne Teasdale, David Steindl-Rast and the former nun Karen Armstrong, and Buddhist monastics such as Ajahn Buddhadasa, Thich Nhat Hanh and the Dalai Lama have taken part in an interfaith dialogue about Buddhism and Christianity. This dialogue aims to shed light on the common ground between Buddhism and Christianity.
Although the prevalent romantic view on Buddhism sees it as an authentic and ancient practice, contemporary Buddhism is deeply influenced by the western culture. With the rise of western colonialism in the 19th century, Asian cultures and religions developed strategies to adapt to the western hegemony, without losing their own traditions. Western discourses were taken over, and western polemic styles were applied to defend indigenous traditions.
In 1989 the Catholic Church, through the Congregation for the Doctrine of the Faith, rejected attempts at mixing some aspects of Christian and Buddhist practices, in a letter titled "Letter to the Bishops of the Catholic Church on some aspects of Christian meditation", generally known as the Aspects of Christian meditation letter.
The document issues warnings on differences, and potential incompatibilities, between Christian meditation and the styles of meditation used in eastern religions such as Buddhism. Referring to some elements of Buddhism as "negative theology" the document states:
Still others do not hesitate to place that absolute without image or concepts, which is proper to Buddhist theory, on the same level as the majesty of God revealed in Christ, which towers above finite reality. To this end, they make use of a "negative theology", which ... denies that the things of this world can offer traces of the infinity of God.