Regardless of a persons opinion or any personal experiences they claim to have had, there is still no verifiable fact on which to form a conclusion to this topic. There isn't really any way that anyone can back up their opinions on Ghosts, Demons, Heaven and Hell.
My Mum is quite a big believer in Ghosts. She told me that a couple of times, she has woken up to see her mother (Who is dead) sitting on the end of her bed. She compared them to bright lights, in terms of how they looked. My Dad is very against the belief of Ghosts, and he won't have any of it, but a couple of times he has woken up too and seen them same thing as my Mum (At the same time as her). I see no reason why my Mum would make this up, and the fact that my Dad can verify it too makes it seem pretty real.
If you're interested in this whole topic, a good book to read is 'Angels in my hair' by Lorna Byrne. It's pretty interesting, if not a little odd.
Personally, I find it challenging to form an opinion on any of these things. I'm torn between the lack of solid, factual evidence and my parents experiences, and everything else I have read on the matter.