A Polemic

1. A person who writes in support of one opinion, doctrine, or system, in opposition to another; one skilled in polemics; a controversialist; a disputant.
2. An argument or controversy.
3. A strong verbal or written attack on someone or something.

(person): controversialist, disputant, polemicist

(strong verbal or written attack): harangue, screed, rant, tirade, philippic