[psyklic]

You have the wrong attitude if you feel that you need to tell customers to "reconsider their own behavior." From this reply, it sounds like you're insulting your customer by pretending to know more about their religion than them. That's not cool.

It is very unprofessional to comment on irrelevant personal information you have stored about a customer.

[natrius]

If you send someone a message on Facebook, the recipient can view your profile. There was no breach of privacy here.