That's exactly the problem - we don't know. There are many elements that look suspiciously like attempts at Christian syncretism, like Baldr's death and resurrection, and Ragnarok (a fiery apocalypse survived by one man and one woman, where one God reigns supreme.)

All we know is that there was Christian influence, because Snorri was a Christian, living and writing in Christianized Scandinavia to a Christian audience.