From "The Atlantic": 

"The words "separation of church and state" are not in the text; the idea of separation is. Article VI provides that all state and federal officials "shall be bound by oath or affirmation, to support this Constitution; but no religious test shall ever be required as a qualification to any office or public trust under the United States." The First Amendment's Establish Clause provides that "Congress shall make no laws "prohibiting the free exercise" of religion. These prohibitions were extended to state governments by the Fourteenth Amendment....

If government can't require its officials to support a church; may not support a church itself; and may not interfere with the worship or belief of any church, is there a serious argument that church and state are not separate?"  

Colorado's Blaine Amendment prohibits public funding of "any school controlled by any church or sectarian denomination whatsoever." That's not anti-Catholic - all religions are prohibited.