I didn't say get into a pissing match with your professor. I said nip this in the bud- first let him know that you don't appreciate his deviation from the course material, you don't think the classroom is where his preachy opinion belongs, and that you would be better off actually learning what the class is supposed to be covering. Tactfully of course. Otherwise- send it up the chain. He has a boss, go to them with the complaints that the professor is interjecting unrelated, non-factual opinion into the course. Someone should have integrity and objectivity somewhere up the chain- if not, well, time to change schools after filing a formal complaint with whoever is in charge of that school.

