At the time the 14tg Amendment was written, passed, and confirmed it wasn't that long a time from the Civil War and people knew who were Confederates and who were not, so it was easy to identify insurrectionists.
Nowadays, we have a whole political party trying to overthrow the Constitution by their support of Trump and his actions prior to and after even to the present of him and his party trying to overthrow the Constitution. We all see it every day, and especially on Jan 6 when it was served to We the People on live TV. I think that's enough.
By their actions will you know them. They are insurrectionists.