There are mainly two reasons that I'm aware of that make a person not believe in afterlife, one is the person's lack of evidence to support the existence of an afterlife and the second is the lack of clear description of what that life really entails. Orthodox religions have only been able to tell us just vague and contradictory description of what life is on the other side. Telling us about reincarnation, virgin wives, lake of wine and eternal praise and worship didn't make us any wiser.
The book "Life in the world unseen" aimed at given a detailed (to some extent) description of what the other side is, though it doesn't necessarily give any evidence to proof that the afterlife exists, it answered some questions people have about what the other side is like.
Since it doesn't provide proof that an afterlife exist you're not expected to belief what it says you can only tell whether what it says is reasonable and likely to be true or not, like an atheist friend of mine who read it said "If there is an afterlife it's likely to be as the book says" but don't take his words for it why don't you find out yourself.
I invite everyone to check it out, religious, non religious, atheist, deist etc.

TABLE OF CONTENT

I. Preface
2. My earth life
3 Passing to spirit life
4. First experience
5. Home of rest
6. Halls of learning
7. Some questions answered
8. Music
9. Plans for future work
10. The dark realms
11. A visitation
12. The flowers
13. The soil
14. Building methods
15. Time and Space
16. Geographical position
17. The lowest realms
18. Some first impressions
19. Recreations
20. Spirit personalia
21. The children's sphere
22. Occupations
23. Famous people
24. Organization
25. Spirit influence
26. The Highest realms

NOTE: Since the book is a narration it is advisable not to read randomly or jump chapters. And don't forget to tell what you think about the book after reading it.

Here is a link to download the book from
http://www.innerpath.com.au/borgia/0Borgiaindex.htm