According to John Hick, the reason God has many names is that since God's general revelation is revealed to everyone the world's religions sprang up as different responses to the divine reality, embodying different perceptions which have been formed in different cultural and historical circumstances. All of these perceptions have their strengths and weaknesses and when they are in dialogue they can learn from one another.
There is a difference between a world religion and an world theology. Hick (like the Dalai Lama) doesn't advocate the abandonment of the religion of your youth in favor of a one universal religion where everyone worships pretty much the same. He does advocate for a theology that interprets religious experience within Christianity as well as in the other "great streams of religious life." These would include non-theistic religions of hinduism, buddhism and even Marxism and Humanism.
Karl Rahner's idea of the "anonymous Christian" is that there are members of other religions to whom Christ has been revealed and so they are saved. The common criticism of this idea is that nothing is stopping anyone from calling Christians "anonymous Buddhists" or "anonymous Muslims." Hick abandons the idea of the anonymous Christian and says that all religions can be viewed as equally salvific if you understand Jesus being God as a metaphor. He says Jesus never taught that he was God. Others referred to Jesus as God because he lived in complete openness to God's Agape love. Since God is love this is kind of the same as saying something like, "Steve Jobs is geek chic incarnate." He says, "Agape is incarnated in human life whenever someone acts in selfless love." I think this is what it comes down to for Hick, as far as we act in self-giving love God is made incarnate in us also.
It is a common belief in inclusivist soteriology that all religions are expressions of God. The closer they come to Christianity the better, and they are not perfect until they are explicitly Christian. In this way all religions are moving toward Christianity.
John Hick speaks of a Copernican revolution in religion. Early astronomers believed all the celestial objects revolved around the Earth. After they started observing these objects in more detail they realized they don't move in perfect concentric circles around the earth. They decided that celestial objects must move in other orbits while ultimately orbiting the Earth. They called these additional orbits "epicycles." In trying to describe the epicycles they become more and more complex until someone (Copernicus) dared to say that maybe all the celestial objects don't revolve around us, maybe they revolve around the Sun. This got him into lots of trouble.
Like Copernicus, Hick says that maybe all religions don't revolve around Christianity but maybe all religions revolve around God. He says this Copernican revolution in religion "must involve a shift from the dogma that Christianity is at the center to the thought that it is God who is at the center and that all the religions of mankind, including our own, serve and revolve around him".