Tolerance is a social contract. If you become intolerant in ways your group does not like, said contract is nullified in your specific case. Which means that when you display intolerance, you will no longer be tolerated.

This is the basic mechanism of social pressure. As social creatures, this is a part of us.

From my perspective, the active problem is that there are no longer any reasonable groups: membership in one means expulsion from the other. This not how progress is made or how compromise is reached. This is how wars begin.

Just my 2 cents. To quote a great singer:

"We’re sick and tired of your ism schism game"