Christmas in its basic forms: --Peace --Love --Goodwill
.......regardless of what one calls it. Do you not agree? Therefore, when I tell folks "Happy Holidays", this is not an exclusion of Christ, but rather an inclusion of those who may fallow a different path. It is an effort to include some of that peace, love, and goodwill to others, regardless of what God may look like to them.
Your "reason for the season" may be optional; my wishes for your happiness are not.
Happy Holidays--whether that be Christmas, Yule, Kwanza, Hanukkah, or whatever you may call it.