Belobog
Belobog is a reconstructed Slavic deity of light and Sun, the counterpart of dark and cursed Chernobog. It is uncertain whether such a deity was ever worshipped by polytheist Slavs, as there are no reliable historic records which mention this name. While in the past a great deal of scholars studying Slavic mythology took the dualism of Belobog and Chernobog for granted, modern research of the matter makes this theory very hard to maintain.
His name is variously given as Bilobog, Belbog, Bialbog, Byelobog, Bielobog, Belun or Bylun, Bielboh or Bialun.
Helmold
In the later half of the 12th century, the German priest Helmold described, in his work Chronica Slavorum, beliefs and customs of several West Slavic tribes who were still polytheists at the time. Amongst other things, he stated that:The Slavs, they say, have one peculiar custom: during feasts, they pass a goblet amongst them in circle, for purpose not to praise, but rather to curse in the names of gods, good and evil, for every good thing praising a good god, and for every bad thing cursing an evil god. This god of woe in their language is called Diabolous or Zherneboh, meaning black god.
On the basis of this inscription, many modern mythographers assumed that, if the evil god was Chernobog, the Black God, then the good god should be Belobog or the White God. However, the name of Belobog is not mentioned by Helmold anywhere in his Chronica, nor is it ever mentioned in any of the historic sources that describe the gods of any Slavic tribe or nation.
Toponymy
Another clue for existence of Belobog is a number of toponyms in Slavic countries which have that name. They include Bělbožice in Czech Republic, Bilobozhnytsia in Ukraine. Sometimes the toponyms are paired with those having the name Chernobog as in the case of hills Bileboh and Czorneboh near Bautzen in Sorbia, and of the Czech Bělbožice which is likewise paired with Černíkovice. This was one of the arguments for the dualism theory.Language
Existence of Belobog is also posited by expression he doesn't see a white god recorded in Serbian language and Macedonian language, and shouting to the white god from Bulgarian language.Slavic dualism
It is further questionable how much the symbolism of white and black representing good and evil — a fairly Christian concept — was important to polytheist Slavs, if they even considered it. From other historic sources describing Slavic polytheism, we for instance know that Svetovid, the god of Rügen island, was symbolised by a white horse and Triglav, a high god in the city of Szczecin, was symbolised by a black one; yet none of them was considered to be an evil or dark deity by people worshipping them. Fourth and final, even if we assume – disregarding all the points noted above – that there really was a Belobog standing in opposition to Chernobog, the question still remains whether these were gods themselves or simply alternate names of some other Slavic deities. Being that Helmold's inscription comes from a very late time, the 12th century, and that it concerns only several groups of polytheist West Slavs, it would not seem likely that these two gods were deities of the original Proto-Slavic pantheon.Peisker's theory of slavic dualism
Regardless, many hypotheses and even more speculations were put forth about the supposed Belobog-Chernobog dualistic structure of Slavic mythology. The most plausible theory concerning this issue was put forth by Czech historian Jan Peisker. In the West Slavic area, he found more than thirty different toponyms which contained representations of some ancient polytheist sacred scene. The structure of toponyms was always the same: a running river, flanked on the west side by a rock with a name indicative of devil, fear, darkness, blackness, hell, and on the east side by a hill or a mountain peak with a name associated with Sun, heaven, light, whiteness.Peisker put forth a theory that these remains of old Slavic sacral places are connected with Iranian dualistic Zoroastrian mythology. On the east side of rivers, a good, white god was worshipped, but the west side was reserved for his enemy, an evil, black god.
Though Peisker's theory does have some merit, and is certainly interesting, its idea of dualism was unable to withstand serious scrutiny.
While Slavic languages are related to the Iranian group of the Indo European language family inasmuch as both went through satemization, and the ancient Proto-Slavs were certainly to some degree influenced by their Iranian-speaking neighbours of West Asia, the idea that the Slavic peoples as a whole are a direct offshoot of Zoroastrian Persians is not only unprovable, but also quite improbable.
Two aspects of one god
Furthermore, the dualistic theories were questioned by the Serbian scholar of myths and folklore, Veselin Čajkanović, who compared the solar deity mentioned in Russian historic sources, Dazhbog, with a far darker and chthonic character of Serbian folklore having an almost identical name, Dabog. Čajkanović pointed out that solar gods in various mythologies tend to have double aspects, one benevolent and light, representing the Sun in the sky during the day, and other malevolent and chthonic, representing the Sun in the underworld during the night. He concluded that two seemingly opposite gods, good and evil, light and dark, could actually be simply two different aspects of a single Slavic deity, Dazhbog.Russian philologists Vyacheslav Ivanov and Vladimir Toporov probably struck the final blow to Peisker's theory with their studies of Indo-European myth about the battle of a Storm god and a Dragon and its Slavic version, the fight of Perun and Veles. In many Slavic countries, there are toponyms reminiscent of the two: The name of Perun is associated with a hill or mountain peak, and the name of Veles with water or a lowland under it. The opposition between the two of them is not that of good versus evil, but rather of above versus below.
Symbolism corrupted by Christian ideology
Perun, being the god of thunder and sky, was worshipped in high places. On the other hand, the places reserved for Veles, the god of underworld and cattle, were in lowlands near rivers or springs.With the arrival of Christianity, the once supreme god Perun was usually identified with one of the heavenly saints, while Veles, being a god of the underworld, had the bad luck of ending associated with the Christian Devil. Thus, christianization somewhat altered certain of these toponyms in that some of them became associated with the devil and hell, while others with heaven and light, blurring their original symbolism.