OK, heard back. I was told my 'church' was not qualified to participate because the guidelines prohibit overtly religious activity. Here are the rules:
Any proposed activity/display cannot serve as an overt political, religious, or propaganda platform and proselytizing is prohibited. Religious affiliated groups and individuals can provide information about international, domestic, ethnic, social justice, and charitable connections. Again, the purpose of this document is to promote and ensure the multicultural and inclusive spirit of the event so as to foster a celebration of harmony and respect for the diversity of the community.
I'm guessing they are pretending to be a charity or teach English. The director said he would investigate, and if they are proselytizing they will not be invited back.