Listen to these sentences at the Talking People Podcast: Useful Language. Communicative Strategies 3
Disagreeing & Challenging an Opinion
I don’t quite agree with that
I’m afraid I don’t agree
I see your point but don’t you think…? (say sth which hasn’t been taken into account)
That may be true but…
You may/could be right but…
You might be right
Are you sure of that? I mean, what data/info have we got to support that?
I find it hard to believe, really.
I can't see your point. Sorry
The problem with your point is ...
I can't see the point of that.
I agree with the first thing you said, but I really can’t see what you are saying now
I agree with your point about (name idea or topic) but not with your point about (name idea or topic)
I don't know... How can you be sure of (that)?
I don't see why, really.
What's your point?
What do you mean?
That's not my point.
That's not the point, really.
I think you're forgetting something. (Explain)
I think you're not taking into account (some issue).
I'm not too sure about that.
I doubt it.
That doesn't sound right to me.
That sounds like a bit too (adjective)....
It wasn't like that (for me) at all.
That wasn't my case.
I used to think that but then I changed my mind because.../when…
Most people think.../say...(that)
I'm not sure I'd go along with you in that...
That's a bit biased, don't you think?
Check out also "Agreeing", "Asking for Clarification and More Info", and "Defending a Position"
Please, for "defending positions" and "attacking positions", read my notes on Discussions in the TP Speaking section - Discussions
More: Agreeing and challenging opinions (read from Natural English)