Unclean Spirits differentiates between the spirits that inhabit spirit prison and hell in the spirit world. The term "evil spirit" applies to those who have never taken a body, while the term "unclean spirit" applies to those who experienced mortality and acquired a body. According to Unclean Spirits, the only spirits completely beyond the reach of the Atonement and condemned forever in hell are Perdition Spirits (scroll down to para. 9), who had a very close relationship with God and then denied Him while in the flesh. According to Joseph Smith, to become a Perdition Spirit, a mortal must receive the Holy Ghost, deny Jesus Christ when the heavens are open to him, know God, and then sin against Him. It is not a singular process.
Unclean Spirits asserts that Perdition Spirits are the most dangerous, because they have the power to inflict physical pain upon those undertaking important missions for the Lord. They've even been known to try and stop children from getting baptized in the LDS Church. The editor of Unclean Spirits reports a personal experience with a Perdition Spirit identified as Cain. Yep, that Cain...the same one who slew Abel:
I had one experience with a perdition spirit who did not attempt to harm me. I was driving about town, lost in thought, when I suddenly felt an unusually strong darkness in the car. I could not see him, but I knew instantly that Cain, son of Adam and Eve, was sitting in the passenger seat next to me. I also knew instantly that he was a perdition spirit. I was afraid because I thought Cain was going to attack me and try to force me to wreck my car to kill me. When Cain did not attack, I calmed a bit and asked him what he wanted. I felt an anguishing sadness coming from him. He asked if I could help him. I told him that I wished I could help him, but he had made choices that prevented it. I said I was sorry for him and he left.
The blogger claims that he receives inspiration directly from God. God answered his request to teach him to protect himself against evil forces by inspiring him to read specific writings from early LDS prophets and apostles that would teach me doctrinal principles about Satan’s tactics. God was very specific in His teaching method: The name of a book and a keyword or page number would appear in his mind. Then he would locate the book and find the passage that God wanted him to read. He would think about that passage and then God would allow him to have experiences that taught him what the passage meant. Then the next book and keyword would appear in his mind and he would repeat the process of finding the new passage and learning from it. This line-upon-line learning continued for several years until he could see how the many separate doctrinal principles fit together.
The editor of Unclean Spirits does not claim to be speaking officially for the Church; he invites us to seek our own independent verification of his ideas through the Holy Spirit. What makes me curious is the God directed him to consult the writings of earlier LDS leaders rather than current leaders. While I believe Unclean Spirits is sincere, the Adversary will frequently use this tactic to sow doubt and bring about apostasy. The Adversary will come to a devout LDS member and assure him that while the Church remains absolutely, positively true, today's leaders have somehow "gone astray" and that he can get to the "real" truth by reading the writings of the earlier LDS leaders. After this is done, the Adversary returns to the individual and tells him he has an obligation to "rescue the Church from apostasy" by becoming the latest "One Mighty And Strong". Before you know it, the individual is shedding innocent blood in the mistaken belief that he's doing the will of God. This is what happened to Ervil LeBaron and the Lafferty Brothers.
One area where I do disagree is Unclean Spirits' suggestion that evil spirits, those who never took on bodies, are not eternally damned. What damns these spirits is not so much that they chose to follow Satan, but that they refused to take on bodies. How can they expect to progress further without bodies? One must have a resurrected body to take up residence in either of the three degrees of glory, so far as we've been officially taught. So for now, I will assume this to still be the case, until I hear differently through official Church channels.
Rules of Thumb:
(1). The four Standard Works are the only official canon of the Church of Jesus Christ of Latter-day Saints.
(2). New canon which supersedes existing canon can only come through the President of the Church via revelation, be ratified unanimously by the Quorum of the Twelve, and be presented to the general membership for a sustaining vote.
(3). If there's a conflict between the current prophet and a past prophet, the current prophet wins. Always.
And one final point. Since only 14 million people in a world of nearly seven billion are members of the Church of Jesus Christ of Latter-day Saints, it may be more profitable for us to minister unto them, and leave the residents of the spirit world to those in the spirit world who have been set apart to minister unto them. The only service we're charged to render unto those in the spirit world is temple work.