When wishing a Merry Christmas, we do not know what we really wish for for at least two reasons.
First, and even though it is what we celebrate by these words, we have no more memory about the message a man named Jesus delivered to his contemporaries; in other words what kind of philosophy and sense of life were behind his actions and words. In brief we can only remember he was born (on Christmas) and died (at Easter).
Then, it is not now and has not been welcome for the last centuries to speak or even mention the existence of any kind of prophet in each main monotheistic religion. These characters seemed so exotic because the future is not discussed and then can simply be ignored, mainly because of the fact that it leads to death, which no longer exists in a technoscientific civilization (sounds as if we will soon be cured of this).
Thus, such revelations are no more than images of past times which do not represent any reality nowadays for the powerful – or insignificant – people which we consider to be. It is probably the reason why we prefer to wish a Happy Holidays Season. « Not to discriminate others », as surveys reveal it to be the reason for not using Merry Christmas, is in fact a way to hide behind them.