Your friends that do not believe in Christmas send you "Christmas cards" because YOU do believe, and they DO sincerely wish you happy holidays.
When it is YOUR birthday, and your friends are aware of it but do not celebrate their own, should they not say "Happy Birthday" to you, or maybe you would prefer that if they see you they not mention your birthday?
Actually, my friends who are not Christian typically don't send me Christmas cards, because it's not part of their belief system, which is fine with me. As I mentioned, they send me Hanukkah cards, for which I am quite grateful. They are also very congenial and accepting when I send them Christmas cards. I don't send them Hanukkah cards, and they've never been offended. If I see them or speak with them on the phone, I wish them a Happy Hanukkah, however, because I care for them and wish them the best.
When it is YOUR birthday, and your friends are aware of it but do not celebrate their own, should they not say "Happy Birthday" to you, or maybe you would prefer that if they see you they not mention your birthday?
I must confess that I am baffled by this question. Could you possibly rephrase it? As far as birthdays are concerned, which are a different sort of day than Christmas, my friends will generally send me a birthday card and I will sincerely thank them. Similarly, I send them a card on their birthdays, and they are generally quite gracious about it as well.