I'd agree with you gromitsk that if someone truly did research into the topic of afterlife they could not assert without doubt that we do not survive physical death.
I've been particularly impressed by Ian Stevenson's research into reincarnation.He's researched many cases where young children remember living another life and have provided many details that later prove to be true. These are extremely well documented cases. I believe he has investigated over 2000 cases. In a typical case a child between 2 and 5 yrs. of age begins talking about a previous life. Usually by 6-8 yrs. of age the child no longer remembers.
Only someone who hasn't studied the evidence in-depth or someone with a completely closed mind can assert that there is no afterlife.