Sorry, atheists - you're officially barred from holding office in my state. Or eight others, for that matter.
That's right, under the Constitution of North Carolina and of eight other states, atheists are forbidden to hold office by the State Constitution. In Arkansas, atheists can't testify in court. And in Massachussets, only Christians are entitled to equal protection under the law.
It's remarkable that only six of the nine states - Arkansas, Mississippi, the Carolinas, Tennessee, and Texas - are traditionally "Bible belt" states. Maryland and Pennsylvania show up. The most restrictive religious test is applied by Massachusetts. (Come to think of it, MD, PA, and MA were all religiously based colonies when they were founded, and so it should probably come as no surprise that their Constitutions reflect that.) And that the state that most people would expect to be hostile to atheists - Utah - has no such provision.
Either way, all of these state Constitutions are in flagrant violation of the U.S. Constitution's Article VI, which states that "no religious test shall be required" to hold office in the U.S. As such, they're completely unenforceable. These provisions are examples of an interesting crossroads of law, one inhabited as well by laws against cohabitation and premarital sex that exist in many a state (up until recently, NC was one). They are laws adopted in the past to reflect the cultural values of a society that are now, thanks to cultural changes, too embarrassing for states to enforce. But at the same time, repealing these laws or amending the Constitution to scrap these clauses would still strike too much of a nerve among the more traditionalist elements of the populace for it to be undertaken. Such idle laws are an interesting phenomenon - to me they serve as proof that it's a bad idea to try to legislate cultural norms.
Another thing. Thanks to judicial review, these laws would be struck down if they were ever challenged (see: NC's cohabitation law). This leads to a fun little koan: these laws are only laws until they are enforced. Then they are no longer laws. That amuses me.
There is, of course, still a practical barrier for atheists to be elected to office in many areas. (In fact, it's probably easier for an atheist to get elected in MA than in a lot of other states that don't have an anti-atheist clause in their Constitution.) But that's another discussion entirely.