Excerpts from Wikipedia:
Ron Karenga created Kwanzaa in 1966 as the first specifically African American holiday. Although the historical Juneteenth African American holiday had been celebrated since 1867, Karenga said his goal was to "give Blacks an alternative to the existing holiday and give Blacks an opportunity to celebrate themselves and history, rather than simply imitate the practice of the dominant society." The name Kwanzaa derives from the Swahili phrase matunda ya kwanza, meaning first fruits of the harvest. The choice of Swahili, an East African language, reflects its status as a symbol of Pan-Africanism, especially in the 1960s....
During the early years of Kwanzaa, Karenga said that it was meant to be an alternative to Christmas, that Jesus was psychotic, and that Christianity was a white religion that black people should shun. However, as Kwanzaa gained mainstream adherents, Karenga altered his position so that practicing Christians would not be alienated, then stating in the 1997 Kwanzaa: A Celebration of Family, Community, and Culture, "Kwanzaa was not created to give people an alternative to their own religion or religious holiday."....
A Kwanzaa ceremony may include drumming and musical selections, libations, a reading of the African Pledge and the Principles of Blackness, reflection on the Pan-African colors, a discussion of the African principle of the day or a chapter in African history, a candle-lighting ritual, artistic performance, and, finally, a feast (Karamu). The greeting for each day of Kwanzaa is Habari Gani? which is Swahili for "What's the News?"
Evolution in Kwanzaa's observance:
In 1977, in Kwanzaa: origin, concepts, practice, Karenga stated that Kwanzaa "was chosen to give a Black alternative to the existing holiday and give Blacks an opportunity to celebrate themselves and history, rather than simply imitate the practice of the dominant society."
In 1997, Karenga and the community evolved, stating that while Kwanzaa is an African-American holiday, it can be celebrated by people of any race: "Other people can and do celebrate it, just like other people participate in Cinco de Mayo besides Mexicans; Chinese New Year besides Chinese; Native American pow wows besides Native Americans."
Currently, according to the Official Kwanzaa Web Site (written by Karenga and maintained by Organization US, which Karenga chairs), "Kwanzaa was not created to give people an alternative to their own religion or religious holiday. And it is not an alternative to people's religion or faith but a common ground of African culture...Kwanzaa is not a reaction or substitute for anything. In fact, it offers a clear and self-conscious option, opportunity, and chance to make a proactive choice, a self-affirming and positive choice as distinct from a reactive one."
Karenga's most recent interpretation emphasizes that while every people has its own holiday traditions, all people can share in the celebration of our common humanity: "Any particular message that is good for a particular people, if it is human in its content and ethical in its grounding, speaks not just to that people, it speaks to the world."
Seems it was started as a "black power" movement to shun the man, and be separate from other cultures. They quickly back pedaled on that when support for separatism was lost, and only then did it start to become mainstream. BTW, it's only celebrated in America, and they light a candle holder that looks strangely like a menorah.
I got my Jesus on the dashboard, but the Devil's under my hood!