I recently got an email from a middle school teacher asking for help. A parent was complaining, for religious reasons, that The Adventures of Ulysses (a middle grade version of the Odyssey) was inappropriate reading for her child.
This is certainly not a new debate. It is, in fact, the oldest debate in Western Civilization. Since the days of the Apostles, and later St. Augustine, we've always had an uneasy relationship between Classical mythology and Judeo-Christian values. As a culture, we tend to believe in one God, but we also grow up steeped in these wonderful old stories about the Olympians. Personally, I don't see any harm in learning mythology as long as we recognize the myths as stories that are part of our heritage and long-since stopped being any kind of serious religion. If fact, I think you have to know Greek myths to understand where our modern culture came from. It's part of being an educated member of society.
If censors want to challenge Greek mythology, they'll have to censor a good portion of the English curriculum in every state. Greek mythology is studied extensively from grades 1-8, not to mention the Iliad and the Odyssey in the upper grades. English literature draws heavily on Greek mythology. It always has -- from Chaucer all the way to modern novels.
For those educators interested in defending the use of mythology in the classroom, I would recommend the National Council for Teachers of English website. Their anti-censorship resource center has wonderful articles on writing curriculum rationales and defending your choice of texts:
http://www.ncte.org/about/issues/censorship
I would also recommend my own teacher's guide for The Lightning Thief, which includes a rationale for the use of the novel in the classroom:
http://www.rickriordan.com/Teachers_Guide_Lightning_Thief.pdf
Good luck, and keep on teaching!