"It may not surprise anyone that the word “God,” “Almighty God,” or similar, is written into the constitution of all 50 states. In most cases, such words are found in the preambles and in the, often required, oaths of office. The mention of “God,” or the like, is used predominantly in reverent thanks or acknowledgment of a divine goodness.
However, what most people do not realize is that eight of the states also include a religious component to a citizen’s eligibility to hold public office and, in two cases, to testify in court or serve on a jury. These states include Arkansas, Maryland, Mississippi, Pennsylvania, Texas, Tennessee, North Carolina and South Carolina. While the language of each state’s “religious test” is slightly different, the ultimate idea is the same. In all cases, the laws exclude the Atheist from participating in officials roles. Beyond that and depending on one’s beliefs, these constitutional regulations could potentially exclude many citizens of minority faiths, including Pagans and Heathens."
Excellent article on the history and laws concerning religious beliefs in America -- and how some who hold office blatantly defy the constitution, clearly believing their beliefs trumps all.