Oops, I realise I left out some info that could go into either Rule 6 or 7.
Anyone who disagrees with the fundamental statement is clearly unable to recognise and accept what is True. This will be because they are reacting emotionally, taking things personally and clearly having their feelings hurt. Point this out. If they deny it, that's a clear indication that this also is True.
You could also apologise for causing them pain by again pointing out the obvious Truth of the original statement, that one that they still find so difficult to accept. But avoid engaging in any debate of the original topic; remember, the premise is True and as such does not require further discussion.