So God had to have a normal mortal to head his church. Plus they were not in charge of the Catholic church, so it could be argued that the church fell away, even if those people were still alive.
The real answer is that people never die anyway, right? And the good ones take their bodies with them, and Elijah never tasted death, Mary was assumed into heaven while still alive, and so was Moses, so there's a whole ward right there of the undead running around.