I am beginning to feel that it is fruitless to try to argue with people who are so convinced that they are the voices of tolerances and liberalism that it is okay for them to treat others in an intolerant and illiberal way
That's an insult, no? It's not exactly helpful, uniting or restorative talk, is it? Plus it's nonsense - I don't know any remainer who would claim to be the 'voice of tolerance and liberalism' - (not sure where that's come from, unless you are extrapolating from one poster to judge all) and its even more nonsense to say they are 'treating others in an intolerant and illiberal way'
I see it as less of an insult and more of a critism 
I think there is somewhat of a difference between calling people stupid, and criticising them for calling people stupid.
As to where I get the "tolerance and liberalism" malarky from, well that is how I see much of the more militant remain folk present themselves - that they are for tolerance, being outward-looking, respecting and celebrating differences etc etc. Then I see the very same people displaying exactly the opposite of these values to people who voted differently to them.
I am not talking about all remain voters - there are plenty of remain voters, including on here, who do not do this. I am talking about the ones who do do this.
You may not have observed this phenomenon of some remainers presenting themselves as the voice of tolerance and liberalism. I have.