With apologies to my legal and political friends (but this is funny, no matter who you are):
The real reason that we can’t have the Ten Commandments posted in a courthouse is this —
You cannot post Thou Shalt Not Steal, Thou Shalt Not Commit Adultery, and Thou Shall Not Lie in a building full of lawyers, judges and politicians. It creates a hostile work environment!
[Often attributed to George Carlin and sometimes to Larry the Cable Guy, but evidently not actually by either of them.]