The term "religion" is controversial in etymology and multivalued in its content. There are many definition types of religion expressing the private opinion of a thinker or dictated by the social and cultural context of the time period. But it is hard to find the right definition which reflects in its entirety the diverse role that religion played and plays in the lives of both its followers and humanity as a whole. Even if we enumerate all the variety of forms and characteristics of phenomena that are regarded as religions, then in this case the definition of religion will be formal. So in fact an adequate analytical-logical definition of religion is not possible at all.
In antiquity, the Latin term “religio” had a different (narrower) meaning, and then those phenomena which attributed to religion now were not associated with this term, and they were called more specifically. For example, the Greek language had the special term “θρησκεία” (veneration of God) and “λατρεία” (worship, cult). Beliefs, piety, practices, etc. were indicated separately. In modern translations of the Bible and related texts, the term “religion” often translates words, which are in the primary source means “fear of God”, “piety” or something like that. When in the V century St. Augustine of Hippo spoke about religion (lat. religione), he mean concrete ideas and related practices. But so far no one has correctly formulated the unifying principle, which makes system of ideas and practices “religious” (belief in supernatural, “ultimate concern” of a person or something else?). Always there are any historical examples that do not fit into theory, and definition of religion.
Wide and universal meaning of the term “religion” began to be attributed only from the XVIII century, when the ideology of the God-fighting atheism matured in European culture. The term “religion” was needed as an abstraction, denoting everything that is opposite to atheism. But this term is very inaccurate because of its abstractness, as an abstract “religion” does not exist. More or less correctly, we can speak only about a particular historical “religion”, about its context and its specific individual characteristics.
Sometimes the term “religion” is generally wrong because phenomena that are considered as religious, in fact, to religion may not apply, or vice versa, what is put out “beyond the brackets” of religion, can have a religious essence. In this sense, the term “religion” have the same problem as the concept of a biological “species” — in some cases they are both inapplicable.
On the one hand, not everything that is traditionally called “religion” is a religion in essence. Let‘s take Christianity as an example. The question — why Christianity is not entirely correct to call a religion will be discussed in a separate article. But the irony is that, besides Christianity, “not quite a religion” is much more. For example, Hinduism and Buddhism.
Hinduism is not a religion, but a way of life according to a certain law. Hinduism no one founded (there were no prophets), and even the exact time of its origin is unknown. In it there is no basic doctrine, central authority and the main idea. And the very term "Hinduism" in the Vedas does not occur. Already in the later period, “fusion” in one doctrine of religious and cultic characteristics of various practices began to be called “Hinduism”, that is, syncretism is characteristic of it. Hinduism has collected many philosophical and cultural ideas, as well as traditions with a common belief in the laws of karma and reincarnation, in the possibility of liberation from the cycle of births and deaths by the way of righteousness. Of course, Hindus believe in supernatural beings. However, these deities do not participate directly in human life. Karma is a philosophy that is not directly related to the deities. It is based on the theory that some impersonal forces (like the “laws of nature”) react to every action of a person, and sooner or later a person has to face the consequences of his actions. One of the parts of Hinduism (the philosophical school of the Nastika, containing elements of atheism) gave rise to Buddhism, which can also be called philosophy, and not religion.
An even greater puzzle for those who wish to to define the phenomenon of “religion”, to classify and decompose everything “on shelves” is Confucianism. In it there is no clear boundary between philosophy, religion and atheism. Therefore, it is sometimes regarded as a religion, sometimes as a philosophy, sometimes as atheism. The fact is that Confucianism is inhomogeneous: already since the III century before Christ there are about ten different directions created by disciples and followers of Confucius. On the one hand, over two thousand years Confucianism in China played the role of the main religion. Its significance and influence is analogous to the influence of the Catholic Church on the life of Europeans in the Middle Ages. On the other hand, Confucianism influenced the philosophy of Germany (monarchical liberalism) and France (the ideology of a revolution aimed at destruction), formed the views of the “prophets” of atheism (F.M. Voltaire, D. Diderot, S.L. Montesquieu, P.H. Holbach, and others). All Confucian doctrines do not contain an unambiguous doctrine of God the Creator and the creation of the Universe. They also do not talk about the immortality of the soul, about paradise and hell, and the posthumous retribution for the affairs of man is attributed only to his descendants. Some researchers argue that Confucian cults have no religious meaning. Moreover, since the XVIII century Confucianism was said (Pierre Poivre) as an optimal model of management of an atheistic society, since from the point of view of European science and philosophy some of the doctrines of the Confucians are purely atheistic. We should add that in the understanding of the Chinese themselves, Confucianism is a "doctrine," which should not be interpreted in the sense of “religion”. The Communist atheism of the Chinese in the twentieth century has many parallels with Confucianism.
The problem of the term “religion” is also that “not religion” (in the classification of atheists) and even its opposite, can have attributes of a religion. For example, Platonism (and its derived forms) can be called a religion. European humanism and the theomachistic atheism that grew out of it are worldviews that have many elements of religion. In general, the concepts of “religion” and “philosophy” have much in common. They are both multi-valued, and it is often impossible to separate one from the other. Each theologian (or philosopher) formulates his definition in accordance with his own system of concepts. In an infinite number of phenomena called “religious” or “philosophical” or “atheistic,” the various features play an unequal role, and some are completely absent.
Therefore, any talk about religion should be preceded by a long preamble explaining what meaning will be invested in the concept of “religion” and about what kind of religion it will be spoken. Otherwise, further arguments will be pointless and weak
The conditional “body” of religion is formed around the central idea. In Christianity, the central idea is personal filial relations with the Creator, in paganism — the usage of certain forms of magic in order to appease the higher powers or put them to service. In Buddhism, the existence of the non-material world is recognized, but the man deliberately distances himself, moves away from it and closes in himself. It would be incorrect to call such different views and worldviews by one term.
In conclusion, we emphasize once again that the notion of “religion” was artificially given a broad and universal meaning (contrary to etymology) only in the XVIII century. This was done by atheists for polemical purposes. Because of its abstractness, the term “religion” does not say anything at all about anything concrete. To the religion began to include a variety of phenomena. Some of them are mutually exclusive and irreconcilable, while others may be syncretic (the fusion of several beliefs and doctrines). For example, the views of different religions on the non-material world and spiritual beings can be very different and even be opposite. For some religions, the main issue is the relationship of God (gods) with people, others, although they recognize the existence of deities, but in a real religious life of a person this is not reflected in any way (a person lives by himself), third religions do not recognize the immortality of the soul and border on atheism. We would generally prefer to abandon the term “religion”, but volens-nolens are forced to use it because of polemics with atheists.
 Especially in English.
 For example, Acts. 17:22 “Then Paul stood in the midst of Mars' hill, and said, Ye men of Athens, I perceive that in all things ye are too superstitious”. In Greek: «Σταθεὶς δὲ ὁ Παῦλος ἐν μέσῳ τοῦ ᾿Αρείου πάγου ἔφη• ἄνδρες ᾿Αθηναῖοι, κατὰ πάντα ὡς δεισιδαιμονεστέρους ὑμᾶς θεωρῶ».
 Augustini Hipponensis episcopi. De vera religione. PL 34, 121–171. — Paris, 1845.
 In other words, the abstract concept of “religion” was created by atheists of the XVIII century to identify themselves. Therefore, the term “religion” is so inaccurate and alien to people who believe in God. In Christianity, Islam and Judaism instead of the concepts “religious” / “irreligious” always used the concept of “faithful” / “unfaithful” (in relation to God).
 These parallels are not ideological, but methodological. In the communist era, Mao Zedong, Confucianism in China was blamed as a teaching. Confucian philosophers were forced to "repent of their mistakes" and officially recognize themselves as Marxists, but in fact they continued to write the same thing as before the revolution.
 In any case, if we call Hinduism a religion, then and Platonism too, since there is much in common between them.
 By the "body" of religion we mean its external manifestations in the social rules of conduct, worship, rituals, rites, etc.