That leaves out at least a few million muslims who have never even heard of him, a few million hindu's and a few million buddists.
Not true at all. Most muslims accept Jesus as a prophet, but do not place him above their own. As do Buddists, as do Hindus. Go and ask a selection of people of different religious backgrounds. Plus, the Bible has been translated into so many different tongues and has spread across the globe. It's message is pretty straight forward (aside from the visions of course) and the moral code sound. Therefore 'most' people have knowledge of Jesus and his message for the earth.