After learning a little about Norse mythology and Germanic people, I was wondering if and to what extend the Bible or Jewish/Christian stories had an impact on nordish myths? I'm thinking in particular about the saga of Odin sacrificing himself to himself on the world tree, being pierced with a spear in his side. I can't help seeing a connection to the crucifixion of Christ here. Coincidence or direct influence of Christianity from the Roman Empire?

Thanks.