One Ear One Tongue

How do you expect to make religion one? It will be one only in the next world, at the resurrection. As for this present world, it isn’t possible here, for here each religion has a different desire and design.
Here unity is impossible. It will be possible only at the resurrection, when humanity becomes one and all people fix their eyes on one place, and all have one ear and one tongue.” 
Fihi Ma Fihi - Discourse 7 -
A. J. Arberry