For those of you to lazy or too brain dead to care. Not one place in the constitution of the United States of America does it mention "separation of church and state".
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
Thomas Jefferson wrote the phrase in a letter to the Danbury Baptist's on January 1, 1802.
"...I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should 'make no law respecting an establishment of religion, or prohibiting the free exercise thereof,' thus building a wall of separation between Church & State."
Now as I mentioned above it is not in the constitution but the rule as written says that our government shall not touch the subject of religion to either encourage or discourage its use by the people of the nation. Religion is a personal experience that you as an individual can choose to share or keep hidden within your life. Do not let it cloud your opinion of those around you who may have a different thought on the matter.