In his trial before Pontius Pilate Jesus tells the governor that his kingdom is not of this world. How does kingship work in "the other world"? Not by demanding obedience and ordering people around. Jesus' strategy for conquering our hearts is vey simple - he loves us.
Over and over Jesus says to us, "You are precious to me. No matter what you have done nor how low you have fallen, I cherish you. I care what becomes of you." His strategy works. Such love is irresistible. We surrender. His way of loving takes over our lives.
How his rule will spread when every Christian on earth loves as Christ loves.