If the view that we're all just praying the same god, is what GW Bush really believes, then perhaps all those Masonic/Illuminati conspiracies have something to them. The Masonic fertility cult believes that all paths lead to god, although they'll couch it in misleading Christian-sounding rhetoric.
While some folks will quickly say "the Bible says whatever you want it to", they probably haven't picked up the Bible themselves to read it and check it out.
The reason the Apostle John wrote his Gospel was to establish the absolute divinity of Jesus. Granted, the concept of the trinity is hard to get one’s arms around and to some degree is beyond human intellect. I think John Calvin comes closest to explaining it in Book 1 of his “Institutes of the Christian Religion.”