Inquire as to whether the customer would like a holiday greeting or not. If the customer answers "Yes", inquire as to whether they would like a religious greeting. If the answer is "Yes" inquire as to what the religion is.

Now the CSR reviews the answers the customr typed in. Obviously the CSR has all the information they need at this point to act the appropriate way. If the customer doesn't want a holiday greeting, the CSR smiles and enthusiastically says "HAVE A NICE DAY!". If the customer wants a non-religious holiday greeting, the CSR says "HAPPY HOLIDAYS!".

etc etc. Problem solved.

Happy [insert greeting here], people!