C.S. Lewis was once asked, what is the difference between Christianity and the other world religions. Lewis responded, "That's easy. It's grace." The story of Jesus is about God coming to us in a great act of grace. The other major world religions are about persons trying to achieve acceptance with God (or gods, or some God-concept) by means of their own deeds. I believe this is why Christianity today is the only real global religion, impacting all cultures.
I saw this firsthand in visits to India and Singapore. Hinduism, Buddhism, and Chinese primitive religion all teach the need for persons to do good deeds in the hope they will be accepted by God or the gods. As I sat in a village in central India and told the people that, with Jesus, there is no "caste system," but that God loves all persons by his grace, I sensed great hope in their hearts. It is easy for me to see how religions based on particular laws and deeds remain mostly culturally localized, while the message of a loving, gracious God who has come to us spreads all over the planet.