全体的には同じ意見だが、一点だけあなたと違う意見があるって英語でなんて言うの？

During a debate, you want to say that you mostly agree, except for one point. You can try one of the above-suggested comments.

I mostly agree with what you said except for that last point...
Meaning that you do not agree with everything that was said.

I agree and I disagree!
When you agree but not with everything, you can use this.

I agree with everything except for one point. - This would be one of the simplest ways to say this sentence. The word "except" means 'not including' or 'other than'.

On the most part, I agree, but I don't agree with one point. - "On the most part" is another way of saying "mostly"or "almost all".

When you want to tell someone that you mostly agree expect for one point then a good way of doing this would be to say "I agree with everything your saying except for one point" By saying this would mean you agree with all the person is saying except for one point.

If you think the same as someone else then you can also say you 'agree' with them
If you agree with alot of what is being said then you would say 'I mostly agree'
When saying that it is one point you don't agree with you can say 'there's only one point I don't agree with'

Here are two ways to say this.

1. I agree with you on all but one point.
   Agree - To have the same opinion on a topic or idea.
   All but - except for, everything except, in every way but this, etc.

2. I can agree with you on everything, but this point.
   Can - meaning you are able to do something. Here you are able to agree on a part of what is said.

   But this point - This point you cannot agree with or on.