Juvari

How extensive was the contact between the vikings and frisians? Did that change due to the frisians being forced to convert to christianity by the franks?

I never really heard anything about frisian viking relations which surprises me because they were both germanic pagans who lived and traded off the sea.

Not a historician, but im fairly sure thats not really what happened. AFAIK there are theories that those pantheons descend from old indo-european pantheons and thats why there are similarities. But Norse gods are pretty much Germanic gods (Odin = Wodan etc), and their belief is just as old as the roman pantheon (who took it from the greek).