I know that many Christians will speak disparagingly of spiritualism and I am sure there is a great deal of fraudulent activity in this. But 1 Samuel 28:5-19 demonstrates that this practice of supposed mediums allowing people to speak to the dead is a very old one, as does 2 Chronicles 33:6 and Isaiha 8:19. Of course that this is mentioned in the Bible should not be construed as either authenticating it or condoning it any more than the mention of slavery constitutes an endorsement of slavery. But this passage in 1 Samuel says that the woman saw Samuel and so what shall we make of that? And for that matter, even in the gospels there is an account called "the transfiguration" where Jesus speaks to people that we know are long dead. So where do you think Christianity really stands in regards to these ideas and beliefs?
Well here is my point of view anyway:
Do I believe that there are people with the power to conjure spirits? No. I do not believe that there is or ever could be any reliable form of commnication possible between spirits of the departed and the living. But do I believe that there are spirits? Yes, and I believe interaction between spiritual and physical is possible but extremely limited and difficult, because God and the angels are spirits and they do accomplish things in the physical world.
The word "spirit" suffers from a great lack of precision and many uses in the Bible seem synonymous with mind, life, feeling or indeed any invisible force or agent. Nevertheless there are numerous examples in the Bible of spirits posessing people and speaking to God and commanded by God (e.g. 1 Kings 22:19-23) and other examples of the spirits of the dead even those of specific people doing various things like speaking to living people (eg. 2 Kings 2).
I think that the Bible teaches that we have a spirit (1 Cor 15:44) that this spirit is our true self (Proverbs 20:27, 1 Cor 2:11) and is eternal in nature (Gal 6:8, 1Cor 15:42-50) and that it continues existing when the physical body is dead (Luke 8:55), but this does not mean that the spirit is not subject to death for it can die even while we are yet physically alive(Luke 9:60, Genesis 2:17). This suggests (and is supported everywhere in the Bible) that the death of the spirit is not an ending of the spirit, but a continued existence without life, either to contrast a state of torment called hell with the promise of eternal life or to say that it can be brought back to life or resurrected by God.

