if your an atheist the only way you would become religious, is if your brain had some kind of trauma, ie blow to the head, lack of oxygen, lobotomized, if these people were real atheists, and they really imagined this happened to them, it could only be because of a trauma to the head.
however if three or more people, under laboratory condictions, all in different parts of the world, had comeback at the exact same time, and had seen the exact same things, and related it back verbatum, then it would be very hard to refute.
so I would'nt put to much belief, in an afterlife.
oh and welcome to sciforums, all for one.