The thesis first gives background information about the general development of fundamental rights in both Germany and the United States and specifically the freedom of religion. The analysis discusses in particular freedom of religion granted by Article 4 of the Basic Law in Germany and the religious clauses of the First Amendment of the American Constitution. In the first conclusion, the differences in the interpretations of the religious clauses both in Germany and the United States will be stated. These differences will then be illustrated by a discussion on the Church of Scientology through its basic facts, history, ideas, and attitude. The most important German and American court rulings will be provided which confront the issue of whether or not the Church of Scientology is legally defined as a church. Even though the American courts do not provide a definition of religion, the Internal Revenue Service does. The issue arises whether or not Scientology meets these requirements. In an excursus, the thesis examines, whether Scientology theologically is a religion. Finally, there will be a discussion of German constitutional issues regarding the Church of Scientology. The conclusion states that Germany does not neglect the fundamental right of religious freedom in its actions against Scientology but protects its relatively young democracy from the threat of extremism and fundamentalism; whereas the United States is able to grant more freedom due to its better established and secured democracy, it still has some control through the scrutiny of the Internal Revenue Service.