We hear a lot these days about a divided nation. So I began wondering this week why our nation has begun to embrace a relatively new celebration known as Kwanzaa, which is not as innocent as it appears on the surface. Launched in 1966, Kwanzaa is celebrated for seven days, beginning Dec. 26. The weeklong festival was introduced by Ron Karenga (aka Ron Everett), a black author and Marxist devotee, who has a very dubious history. Mr. Karenga's Marxist roots should be a warning signal right off the bat, but there's more to be concerned about here. In 1969, on...