No, it wasn't, it was to prevent the federal government from establishing a mandatory religion, or just one financially supported by the taxpayers. States were free to do that, and many did at the time.
Anyone who can read English can determine that meaning for themselves.
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof;"
Respecting an establishment" means no State established or supported (financially) religion. The second part, the part mostly ignored in a misreading of the first part, is pretty clear, the federal government cannot prohibit the exercise of religion.
But Cain's statement is indeed in violation of the Constitution, although not the amended version of it.
"no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.Art VI, third paragraph, Constitution for the United States.
AND JUST WHY did the founding fathers not want the government to establish a mandatory religion?
Was it because they feared the religion would then be used to control the government?
Are there any examples you can think of where the government has established a mandatory religion? Like countries in the middle east?
In those cases, does the government control the religion, or the religion control the government?