Some souls can be very confused after they have died if the circomstances around their death were very strange or if the death was very unexpected. Most souls however are aware that they are dead, even the ones from retarded xians/muslims/etc.
It may take the soul a while to figure out exactly what had happened and to understand they are in fact dead.
However they usually don't linger long in this state of half awareness. If the person is fully aware of his/her inpending death at the moment of passing they most certainly know they are dead after they pass.
If you run into a spirit who doesn't know they have passed yet they are most likely to be in a state of confusion and might be scared etc. If you can communicate with the deceased you can speak to them and councel them to make them aware of their situation and then you can ask Satan to guide them to hell, even if they were previously xian or muslim. The souls of the deceased have the same personality as when they were alive and they can still suffer from the same pains or stress that affected them before they died. However they don't experience physical pain ofcourse.
Souls of the deceased can often see the truth much easier though, because they are looking from a different perspective, from the astral perspective.
Not very long ago I lost a person I cared about, she committed suicide after suffering from depression and the like. The saddest thing of all was that she has a satanic soul. I have since spoken with her a few times and she has gained a lot of clarity regarding the truth about Satan and the like after she passed away. In life she never got the chance to dive in the occult and spiritual, but I often spoke with her about this. She didn't understand much of what I said back then, but after her death she spoke to me and told me she can see what I mean now and could also sense my power and energy now. As a result she carried a lot of regret at first, but I asked if Satan can guide her to hell and that is where she currently resides, she was able to let go of her regrets and move on safely.
HAIL SATAN!