Well, Sabbath came out with their first metal album in February of 1970, back when hippie music and peace was huge for society. For such a dark album with very satanic lyrical themes to come out in such a time, to society at that point it was like "this shit is scary man, wheres my White Album?" It shocked a lot of the people who bought it, and that wasn't even the goal of Sabbath. They just wanted something heavy. They guys in Sabbath weren't even sure what to classify the genre as, until one review said it "sounded like a pile of heavy metal being dropped" and then fans of the genre took that in as it's name. Now, back when metal got HUGE (1982-1990) there was much resistance, and a few American mothers got all butthurt and mis interpreted the lyrics of pretty much every metal song that came out. Not to mention how the churches reacted and how Brazil banned Iron Maiden from playing in the 80's.

(I shall expand more on this tomorrow, my iPhone is dying.)