Final answer:
Most of what we know about Norse mythology comes from works written after the Norse had converted to Christianity. However, the Norse people retained elements of their mythology even after their conversion, as seen in the decorations of early Scandinavian churches.
Step-by-step explanation:
Most of what we know about Norse mythology comes from works that were written between the eleventh and eighteenth centuries, after the Norse had already been converted to Christianity.
The Norse people, who were originally polytheistic and worshipped deities such as Odin and Freyja, eventually converted to Roman Christianity.
However, their conversion did not mean a wholesale abandonment of their existing culture and tradition, as early Scandinavian churches were still decorated with images from Norse mythology.
Learn more about Norse mythology and conversion to Christianity