The Norse offered the early Christian settlers of Europe protection. In exchange, they were made powerful, important figures. I know because I am descended from the first Duke of Normandie who was of the first generation that was baptised. Some became kings, or married the daughters of Kings. They went on to support the Templar, Freemasonry, took part in the Crusades, etc. The first Grand Master Masons were Scottish, of Norse descent (the St. Clairs). Don't act like it wasn't their choice. Much of the imagery and early symbology incorporated into Masonry is Norse, along with Christian, Egyptian, Celtic, etc. Think of it more like an evolution of their belief system ;)

Edit: For what it's worth, I recommend you all spend some time looking into your ancestry. It is not only fascinating, but also helped turn me on to my life's purpose... which is, in part, to undo some of the damage my naive ancestors did.