1. a controversial argument, as one against some opinion, doctrine, etc.
2. a person who argues in opposition to another; controversialist.
3. Also, polemical. of or relating to a polemic; controversial.)
Citations for polemic
The second [book] is an angry polemic against the pervasive corruption of representative democracy wrought by economic inequality.
Jonathan A Knee, "The New Gilded Age in Philanthropy," New York Times, May 1, 2017