I think you should be polite and respectful because if you are disrespectful to this one prof, word will get around the school. If you are asked for an opinion, you can take your time to form a good answer. Hedge your bets. Explain that you know there’s a lot of ideas out there, maybe mention one idea that you are particularly familiar with but disagree with. Tell him/her clearly about your position on that one and then explain what your opinion is, and why you feel as you do. If you can cite authorities for your various opinions, so much the better. That will show your professor that you’ve given the topic some thought.