Legal Question in Constitutional Law in Georgia

From your post, although it is somewhat vague, you are sending out company cards and not personal cards. Of course the company can dictate what is on company cards (to some degree) and many employers will go with the "Happy Holidays" version. If the situation were a little different, such as requiring you to personally sign and refer to a specific religious holiday that was contrary to your religious beliefs, the answer could be different. If this is the case, you need to re-post with many more specific facts.

Of course they can.