The "Lemon Test"
The law on church-state issues, as ruled upon by the Supreme Court, has evolved and may yet change, but since 1971, legislation and governmental behavior on such matters has been required to meet the "Lemon Test," so named for the case, Lemon v. Kurtzman. To be constitutional, government legislation or action must satisfy three criteria:
It must have a secular purpose.
It must neither advance nor inhibit religion.
It must not result in "excessive government entanglement" with religion.
Applying the test
Although they have not been absolutely uniform in dealing with such cases, the higher courts, including the Supreme Court, and most lower courts have repeatedly concluded that 1) the symbols of Christianity, or those of any other religion (e.g., a Jewish Menorah, a Muslim crescent symbol, a Mormon statue of the angel Moroni, a neo-Pagan pentacle) cannot be displayed on public property unless the symbols of other religions are displayed at the same time, to make it clear that the governmental jurisdiction in question is not endorsing any single religion; and 2) unless the display also includes secular symbols, to show that the state is not promoting religion over secularism. As a result, a city or other government entity may allow a nativity scene on the courthouse lawn, but only if it also includes symbols of other religions such as a Menorah and secular figures such as Frosty, Santa, and a few reindeer as part of a larger "seasonal" display.
These court decisions have irritated the Christians who want to keep doing things the way they always have. Their response has often been to complain that Christians are being discriminated against and America's historic Christian-dominated culture is under threat; frequently, they have identified Secular Humanists as the major force behind that threat. Many secularists and religious people who advocate a strong form of church-state separation have been generally pleased with the decisions. Some members of minority religions have been pleased that Christianity has not been granted a favored status and, in some cases, happy to have their own symbols represented in a conglomerate display. Still others feel the whole dispute not worth the attention it receives.