Everyone who attends the Church of the Nazarene gets asks this question and has a hard time answering. In short, the C.O.N. is a Christian Church.
Some history...
The C.O.N. can trace her roots back to Jesus and his disicples through the Methodist Church, Church of England, Roman Catholic Church and the Early Church.
Some theology...
Nazarenes are Wesleyan/American Holiness people. They are not fundamentalists but are liberal thinkers. They are social conservatives rooted in convictions that desire a holy lifestyle. A common quote, "In essentials - unity, in nonessentials - liberty, in all things - charity."
Some story...
Phineas Bresee, a Methodist preacher, focused on serving the poor in Los Angeles which led to him leaving that church and starting a new denomination. J.P. Widney, the second president of the University of California, was a friend and contemporary of Bresee. Widney suggested the name "Church of the Nazarene" citing it was the name Jesus used of himself and symbolized the toiling, lowly mission of Christ.
Some future...
The core values of the C.O.N. are "Christian", "Holiness" and "Missional". The denomination's mission statement is "to make Christlike disciples in the nations". Nazarenes celebrate their centennial October 5th, 2008.