Well, he didn't have much choice in the matter!

It's important to try and approach the texts from a scholarly position, the prose Edda for example is one of the most complete and comprehensive records of Norse mythology but was written with the intent of providing a framework for court skalds in Scandinavia, written by a Christian for a Christian audience. one thing it's important to understand is that the Norse mythology was almost certainly not practiced on a comprehensive and thorough scale, stories and practices would have varied widely from area to area and over time as well. It's why I find reading the sagas interesting because the mythology is sprinkled through, and presented in a more day-to-day fashion