In the course of the Heroic Age many of the Teutonic peoples were converted to Christianity. The change of faith began among the Goths soon after the middle of the fourth century and must have spread very quickly to the Vandals. The Gepidae and Langobardi seem to have followed the example of these peoples in the course of the following century. At the time of Justinian's accession the Heruli were probably the only Teutonic people in eastern central Europe who remained heathen. In the west the Burgundians accepted Christianity apparently about the beginning of the fifth century, and the Franks before its close. The conversion of England took place in the seventh century; that of the Frisians and Old Saxons for the most part in the eighth. The Northern Kingdoms in general were little affected by the change until towards the close of the tenth century, though the first missionary efforts in Denmark and Sweden began before the middle of the ninth. In parts of Sweden the heathen religion lingered on until late in the eleventh century.

In the Nibelungenlied it is clearly recognised, perhaps through scholastic influence, that the multitude assembled at Attila's court included both Christians and heathens; but no such distinction is drawn in the English and Norse poems. In the former all the characters are made to speak as Christians, though they observe heathen rites; in the latter no indication is given that any of the characters were Christians.