@cm I'm reading the link now - thanks! I think I agree with it but many use the phrase to justify intolerance in general.
From the link:
"for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; they may forbid their followers to listen to rational argument, because it is deceptive, and teach them to answer arguments by the use of their fists or pistols"... or social media mobbing
The big emphasis is that tolerance requires rational argument - open, rational communication between different groups.