[Sarumian]

Russian Wiki contains the next relevant information on the matter:

Some contemporary scholars consider that there was no such a Slavonic deity as Radogost. Their opinion is based on the fact that the matter was first time mentioned by Thietmar von Merseburg, who reported that there was the town of Radogoshch (Radogoszcz, Radgosc) in the land of a Slavonic tribe Redarier (a tribe of Polabian Slavs), in which they had a cult of their main god Svarozhich (Svarožič). Later chroniclers and historians, it seems, used these data only. Half a century later Adam of Bremen writes, in turn, about the town of Redar and the god Redegast. Scholars regard that he made an error and confused the names of the deity, the town and the tribe, while the name Svarozhich is missing. It is known that Svarozhich is a deity's name, common among the Slavs. It is also known that there were many Slavonic names containing -gost, while Slavs did not give their children names after their gods. Besides this, many Western-Slavonic place names end with -gost. All this says that Radogost is a town name, that such a deity did not exist; it came out to be due to chroniclers' mistake only.

Places with name Radogoszcz or Радогощь

The song Svarog by a Russian rock-band Aquarium