Who is your favorite atheist philosopher and religious philosopher?

Who was the Greek (?) philosopher who wrote about the citizens of the world?

• Years ago, I remember studying a philosopher in the Hellenistic world whose teachings had been found engraved on a stone structure.  The writings had to do with how all people of the world were related or deserving of dignity, or something like that.  I want to say it Diogenes, but I can't find anything about it.  Anyone have any idea what I'm rambling about?

• Answer:

  "In fact, the first philosopher in the West to give perfectly explicit expression to cosmopolitanism was the Socratically inspired Cynic Diogenes in the fourth century bce. It is said that “when he was asked where he came from, he replied, 'I am a citizen of the world [kosmopolitês]’” (Diogenes Laertius VI 63)" from the Stanford Encyclopedia of Philosophy entry on "Cosmopolitanism" http://plato.stanford.edu/entries/cosmopolitanism/ By the way, Diogenes the Cynic (also known as Diogenes of Sinope) should be distinguished from other ancient writers named Diogenes. Especially, Diogenes Laertius is the historian whose work contains this quote by Diogenes the Cynic. But they are different people.