Both the Tea Party and al-Qaeda seem to me to be nihilistic movements relying on an imaginary past to rationalize retrogressive politics and whose goal is to remake the political status quo in their own image. Moreover, the imaginary past in defense of which they purport to act is an explicitly political artifice, an ideological narrative, one that has been quite deliberately constructed so as to "prove" what passes for "points" in their respective discourses. And both are equally willing to harm those they claim to defend -- ordinary Americans and Muslims -- in order to advance their respective, peculiar ideology.
So what if the teatards haven't committed (many) acts of violence yet? If a terrorist cell hasn't committed an act of violence, is it not still a terrorist cell? Was Iyman Faris not a terrorist because he only planned to blow up the Brooklyn Bridge? Does that make him a "pre-terrorist" or perhaps a "latent terrorist?"
Tea Party people have committed acts of violence, of course. Many are reluctant to call them terrorists only because no one has (luckily) yet died at their hands.