But if you label terrorists "extremists", where does that leave anyone who has read the Constitution?
Their rhetoric intersects because of the way they have defined the Right.
OH, Hell no! Quit playing games with the language!
Terrorists use terror (the very real bloody, deadly, kind not some snowflake wetting their pants over simply being disagreed with) to further their political aims. Sure, it's a tactic, but it is also a mindset (that murder is justified by their cause), and it is strongly adopted by a host of groups including those whose religious beliefs mandate that they kill their enemies, convert them to their beliefs, or crush them in subjugation, using any tactics against any target.
As such, those are the groups we are at war with, no matter how small or large, and some are of considerable breadth, whether that scope is commonly acknowledged or not.
They are not the people who know the founding documents and principles of our government but have, regardless of their peaceful actions and intent, been labelled extremists by those on the Left who riot, protest, and burn neighborhoods when they don't get their way.
Unless they specifically, individually or as a group, adopt and approve terror tactics or beliefs that endorse them, they are not terrorists. Others, by professing beliefs specifically linked to terrorist actions, and not condemning those actions, may well fit the definition.