Today's Favorite Verse: Doctrine & Covenants 50:31
"Wherefore, it shall come to pass, that if you behold a spirit manifested that you cannot understand, and you receive not that spirit, ye shall ask of the Father in the name of Jesus; and if he give not unto you that spirit, then you may know that it is not of God."
I know that Satan can appear as an angel of light. He and his minions can deceive. This verse made me think back to my near-death experience and when I met him. He was the only one that could see me. He was also the only one I was not given his name or how I was related to him. All I wanted to do is be as far away from him as possible. This experience makes me understand how this verse fits. He is someone "you cannot understand".
As I reflected on the manifestations of the Spirit there is never confusion. It is pure knowledge. The experiences are totally different. I think Satan totally capable of making one doubt themselves. With that doubt you will dwell on him and think it an issue with yourself being "worthy" to understand. With this doubt and confusion you will be taken into forbidden paths. This chapter gives very important guidance.