Our laws demand the separation of church and state so why should we continue to have reference to any religion in a statement repeated thousands of times a day? The line "under god" was added while our country was involved in a cold war with a non religiously affiliated state that we are no longer participating. This line is unconstitutional under the first amendment which states "Congress shall make no law respecting an establishment of religion".
http://www.ushistory.org/documents/pledge.htm
http://www.archives.gov/exhibits/charters/bill_of_rights_transcript.html