mantras, praying and meditation activates pineal gland and pineal gland produces dmt(Dimethyltryptamine - Wikipedia, the free encyclopedia). dmt is said to be the spirit molecule, because it produces mystical states and opens doors to unconsciousness. near death experiences are so close to a dmt trip(in all aspects) that i(and many others) believe that it is caused by it. that bright light(that feels like it contains everything) that people see when they are entering "heaven" is one of these, so is life passing infront of your eyes, seeing or sensing other beings(angels or that guy who is deciding if you get to heaven or not) etc etc.
also i believe that the "heaven" could quite possibly be a dmt trip and your faith guides how you will trip(your whole life and beliefs being a setting for this trip). it could feel eternal because psychedelic substances can cause really massive change on perception of time, even the amounts that people take this for spiritual purposes can make few hours feel like few life times. and the amounts that you get this while dying are massive compared to the amount that people take, and are most likely aimed at the right spots making some aspects of the trip more controlled or maybe it is because your brains dont work normally anymore and are incapable of making out new connections. funny thing about pineal gland is that its just in the right spot that it could spread dmt in brains even without your blood carrying it making you able to have this trip even if your heart had stopped. if this is true that afterlife is a dmt trip, it could very possibly be true that the trip would be heaven or hell like based on your believes or how you have lived your life and this is why religions have this sense of good or bad afterlife.
when looking at religions as an atheist it seems like nearly all of them are misinterpretations of the same thing, just from a different perspective.
pineal gland is also considered as the "third eye" by budhists, hindus, ancient egyptians(who believe that this is where the soul goes out of the body) and many others.
tibehtian book of the dead says that soul enters the body of fetus after 49 days, and researchers have found that pineal gland is developed after 49 days. coincidence?