Simple Examples:
* The author's book is a polemic against the current political system.
* The debate was filled with polemic and very little actual discussion.
* Her speech was a polemic denouncing the use of fossil fuels.
More Complex Examples:
* The film sparked a polemic about the ethics of artificial intelligence.
* His polemic against the use of pesticides in agriculture was widely debated.
* The article was a polemic on the dangers of social media addiction.
Note: "Polemic" can also be used as a verb:
* The politician polemicized against the proposed legislation.
Remember that "polemic" generally refers to a strong, often controversial, argument against something.