The word "pagan" has defined meaning... it does not apply to secular holidays. The Christmas tree found in most homes for the celebration of Christmas is unquestionably pagan. Do you keep a Christmas tree in your home?
Kwanza is as relevant as mother-in-laws day. Kwanza is not the practice of worshiping false god(s). It represents no religion. Negros invented Kwanza to get under the skin of people like you. Seems to be working.
Christians get enough bad press. Perhaps you should pick a better target for your righteous crusade.
Keep in mind that there is no biblical command to establish or celebrate Christmas. Neither is there a biblical instruction against the celebration of "secular" holidays.
As one brother in Christ to another, we must take care that we always remember to profess our faith as much with what we do... and with how we treat others... as we do with our open proclamations of our faith.
Especially in so open and public a forum, our love and respect for one another should above all else be most evident, that we might always shine like beacons of Christ's love for all to see... believer and unbeliever alike.
God bless you, and Happy New Year.