After some research about the Wall of the Faithless, it seems that it's gone from Forgotten Realms in the 4e. So where do the souls of the unbelievers go now?
The 3e Forgotten Realms Campaign Setting says that the souls of unbelievers go into the Wall of the Faithless and can't be resurrected. So in 3e your character had to have a patron deity in order to be resurrected. His/her soul went to the Fugue Plane and then to the realm of his patron deity.
Now the souls go to the Shadowfell (ex Plane of Shadow) and Kelemvor still judges them. But where do the souls go after the judgement if they had no patron deity in life? And most importantly, can they be resurrected?
Edit after comment:
I'm asking this from a "lore point of view", because it seems that the 4e Forgotten Realms Campaign Setting book focuses more on new rules and doesn't change the default rules like the 3e version did.