According to a random footnote in in Amos 7:17 pagan is Hebrew for unclean: "Therefore this is what the Lord says: " 'Your wife will become a prostitute in the city, and your sons and daughters will fall by the sword. Your land will be measured and divided up, and you yourself will die in pagan[Hebrew an unclean] country. And Israel will certainly go into exile, away from their native land.' " The Israelites literally called any nation that wasn't them pagan yet white/European nationalists adopted the term for themselves for whatever reason assuming "pagan Norsemen" is what their ancient ancestors were.