18 U.S.C. § 2331 explains "Domestic terrorism" as activities with the following three characteristics:
1- Involve acts dangerous to human life that violate federal or state law;
2- Appear intended (i) to intimidate or coerce a civilian population; (ii) to influence the policy of a government by intimidation or coercion; or (iii) to affect the conduct of a government by mass destruction, assassination. or kidnapping; and
3- Occur primarily within the territorial jurisdiction of the U.S.
The church of Scientology fits the description of a domestic terrorist organization as per numerous testimonies summarized in HBO's documentary "Going Clear: Scientology and the Prison of Belief."