I think Pastor Jared Wilson has some insight that should be considered on this topic. Here's a snippet of his thoughts. Read his whole post for greater understanding.
I submit that "Merry Christmas" as an empty cliche is equally Christless to "Happy Holidays." And in fact we ought to reckon the perfunctory "Merry Christmas" as more offensive than a cheerful "Happy Holidays," not less.
Why? Because God commands us to revere his name and keep it holy. I don't think getting irked that the clerk at Target didn't Jesusify his mandated holiday greeting meets what this law demands.
I guess what I'm saying is, why do we want to force people to claim our Christ? Let's not foist Christ at Christmastime. We ought to take care we aren't campaigning for Christ's name to be taken in vain! But I fear this is what we're doing.
Boycotting or petitioning to make store salespeople confess Christ to us does nothing to truly honor Jesus. It just puts our preferred religious gauze on what is very often (though not always) moralistic or consumeristic idolatry. It might make us feel better but it does not truly adorn Christ's gospel.