I think he's an idiot.
Do good Catholics call the Successor of Peter “idiot?” I think not. It is disrespectful and shows a lack of charity.
It is one thing to believe what you have written, which is certainly your own business, and it is legitimate to offer criticism, however, insults are inappropriate.
Charity demands one say something like, “I disagree with his remarks, and don’t like either the presentation or the tone. I think he is quite off the mark.” However, insults and name calling are just plain wrong.
Would you like to be called an idiot?