Christendom is Christian civilization. But not all forms of Christian civilization are kingdomcultural. Some strands or forms of Christendom are subcultural and others are countercultural. These worldly forms of Christendom must be continually guarded against and repented of in order for kingdomcultural expressions of Christendom to triumph. A primary dynamic or mark of kingdomcultural Christendom is chivalry.
Also see Chivalry, and Kingdomculture.