The evolutionist and diffusionist approaches were combined in the works of Lubor Niederle and A. N. Veselovsky. Both of them thought that the Slavs did not succeed in developing a higher mythology and had remained on the level of demonology. Other scholars rejected the conclusions of the mythological school for a different reason. They stressed the shortage of available facts and did not believe in the reliability of any of the offered hypotheses (W. Jagič, H. Máchal, L. Leger, A. Kirpichnikov).

In the works by scholars of the 20th century (E. V. Anichkov, N. M. Galkovsky, V. J. Mansikka), this scepticism was overcome, and the analysis of sermons by orthodox preachers against survivals of paganism came to the fore. But following the preachers' vilification of the pagan practices, the scholars involuntarily inherited their bias as well. They still viewed paganism as a rough and primitive belief system. Anichkov, for instance, held that Rus abounded in minor gods (or rather demons) while the powerful major gods were borrowed from the Varangians. In this he followed S. Ruzhnetsky's work on Perun as an imitation of Thor.

In the 20th century, the Polish scholars (H. Lowmianski, W. Szafraňski, L. Moszyňski) picked up the trend emphasizing the primacy of attributes of monotheism in Slavic paganism. One may detect in this the influence of Catholicism. For these scholars, Perun was not simply the main god, but the only god, all others being only his incarnations.

Among Soviet scholars, the official militant atheism had prevented the study of Slavic paganism for a long time. Besides, their obligatory Marxist vitriol was reserved mainly for the major ideological enemies — Christianity and Islam. However not long before the Great Patriotic War (World War II), the interest in Slavic paganism was revived due to the regime's encouragement of patriotism in the country. Four new concepts of Slavic paganism were introduced. In all of them the focus had shifted from using historical records to those provided by ethnography and archaeology.

The first concept was worked out by the official leaders of Soviet science, such as B. D. Grekov and B. A. Rybakov, Members of the Academy of Sciences. According to their concept, the Eastern Slavs (living from the time immemorial on the same territories as at the present) had discovered — some thousands years В. C. — the plough agriculture, created the state, and developed a pagan religion that came very close to Christianity.

The second concept was presented by the officially disgraced scholar, Professor Vladimir Propp, one of the founders of Soviet semiotics (he was one of the leaders of world structuralism as well). Propp has observed that Russian agricultural festivals, which are highly seasonal, demonstrate a stable set of common features (due, he said, mainly to the similarity of peasant working conditions). Since these festivals totally lack any developed gods, the inference was that the underlying Russian paganism was totally devoid of them, being of an especially archaic nature (like in the views of Anichkov, Niederle and Veselovsky). Such figures as Kupalo, Yarilo and the like, were «underdeveloped deities».

V. Propp's opinions added an additional impulse to the legacy of the work done by the Russian ethnographer of the older generation, Dmitriy Zelenin, who had studied Slavic demonology with the retrospective method. His follower was Nikita I. Tolstoy, the grand-grandson of Leo Tolstoy. Member of the Academy of Sciences, he had built an influential school of ethnographers and ethnolinguists. So, the third major concept of Slavic Paganism emerged, aimed at reconstructing the old pagan religion using the exclusively ethnographic material. Naturally it could throw to the past only what remained kept in the living culture, i. e. no major gods. Thus the most prominent professional ethnographers, ethnolinguists, and folklorists have accepted the idea of the ancient Slavs having only lower mythology (demonology).

The fourth concept was offered by Vyacheslav Ivanov and Valdimir Toporov, also structuralists and (if for no other reason than this) considered by the regime as frondeurs. They used the names of Slavic gods as their main source and compared them with other Indo-European names, social terms, and myths. On this basis they began reconstructing a developed mythology derived from the common Indo-European substrate (the «Basic Myth», the initial struggle of Perun against Volos -Veles, etc.). Their methodology was to a great extent borrowed from Levy-Strauss. It allowed them to reach such freedom of making connections that the results of their reconstructions became very rich, but, alas, lost the reliability. There is no direct proof of the struggle of Perun against Volos (and Volos, as distinct from Veles, probably is at all a new god, most likely having emerged as a transformation of the Christian Saint Vlasius/ Blasius, Bulgarian Vlas).

As far as Boris Rybakov's theory is concerned, it is analysed and criticized at great length in this work since it turned out to be the most influential, and until now remains such, particularly outside the confines of the scholarly world. Rybakov's use of material (the entire categories of which he simply lacked the professional qualifications to process) was already outdated at his time and often embarrassingly crude. The conclusions at which he arrived were not just unsound but often simply comical. In spite of all this, however, one must give him his due for his his considerable imagination and enthusiasm for his subject matter.

From the modern perspective, it is worth noticing that his works became the basis for modern neo-pagans, more and more noticeable since the 70s among the new religious movements. Produced by nationalism, in the conditions of the general political and ideological decline of the Soviet regime, as well as the crisis of the Russian Orthodoxy, this movement has ignored virtually all real data on ancient pagan cults and rituals and began to create new cults and rituals, formally combining the elements borrowed from the Indian and Germanic practices and aimed at the propaganda of such primordial cruelties as hatred of the aliens, militancy, isolationism and xenophobic nationalist solidarity. Ecological concerns of the present time (respect for nature) are being hijacked by the new pagans and recruited into their complete disavowal of the principles and norms of civilization.

Therefore, the proper analysis of genuine East Slavic cults and mythology appears important also in the context of clear seeing the alleged basement of the growing neo-pagan movements.

The present work introduces a new source for the analysis of old Slavic paganism, the Vainakh (Chechen-Ingush) folklore. In this folklore there is a character named Pir"on or Pirlon, whose name sounds close to the Slavic name Perun. This Vainakh character was interpreted by folklorists as a deriváte of a Pharao (genitive: Pharaoni; Pir"on might be a Caucasian distortion of the word «pharaon-»). However, by his functions he does not fit this role: he climbs up the heaven, thunders, and pours rain. In this, he is functionally equivalent to the Thunderer Perun. How could he get into the Vainakh folklore, however? In the last centuries, when Russians came to the Caucasus, they were already Christians and Perun was absent in their mythology.