"'''Evolution''' is a [[controversial issue]], with widely differing points of view."
"The '''theory of relativity''' is a [[controversial issue]], with widely differing points of view."
"The '''heliocentric model of the solar system''' is a [[controversial issue]], with widely differing points of view."
My idea with the "controversial issue" flag/page-link would be to use it for articles that are still "contested" at Wikipedia. Many articles that in themselves regard controversial issues have been splendidly NPOVed, and wouldn't need to be flagged.
But others, where people bicker back and forth, or where someone still doesn't consider the article to be NPOVed, would benefit from it.
(I'll write a sketch.)
-- Daniel