The following video is a clip of Ravi Zacharia speaking on this question at hand. He understands why people would like for all religions to be the same, but he presents why they all cannot be the same or all be true by showing their fundamental differences.
The following video shows that the world's religions are not all the same. There are essentially two categories for the world's religions - "free" and "not free."
This video shows the contradictions within the religions, showing that they cannot be the same. It also shows that they cannot all be equally valid paths.
This video evaluates different religious views on the existence of a personal God, the subject of salvation, and the view of who Jesus is.
This video shows the different answers that people give on the spot when interviewed out and about in their community.