The personality, memory and cognitive abilities of a human being (or animal), that is the various qualities attributed to a "soul" that supposedly survives physical death, have now been understood in medical science to merely be functions of the expansive neural network in one's brain. As such, when this brain stops functioning, these qualities immediately stop functioning as well.
Science has not yet found a way to read memories stored in the brain's neural network (dead or alive) or restart the personality stored in it, and it may never find one at all. But it has already been shown with enough evidence that without a functioning brain, there would not be any functioning personality, memory or any other cognitive ability.
The conclusion of this is that, a soul cannot exist as the qualities of a soul (personality, memory, both or anything else) all depend on a functioning *biological, physical* brain. Therefore, nothing survives beyond physical death except the dead body. And once a body is dead, it starts decaying.
The religious are looking for life beyond death and finding vain hopes and empty dreams about an afterlife they like in the religions they pick. Everything people believe about afterlife are just that - beliefs - fueled by wishful thinking.
Atheists on the other hand accept the reality that there is no afterlife and stop looking for one. Instead, they concentrate on using this life for the better while it still lasts. In the end, an atheist and a theist will both be dead. Nothing beyond it, except the decaying bodies of course.