A few years ago, there was an exhibit at the Museum of Natural History in New York City that highlighted the issue of bioluminescence in various insects and organisms. The fireflies were the most interesting. Apparently a chemical is produced in their lower abdomen that interacts with enzymes and other chemicals to produce light. Glow worms are the larvae for fireflies and they also produce bioluminescence.
It seems that the devil and his angels have been engaged in extensive genetic research focused on programming certain human genes to facilitate the production of light. Thus, when you observe certain individuals in the spirit realm, they appear luminescent, so as to mimic the light that radiates from a person with the indwelling Holy Spirit of God. However, they merely have been genetically programmed to produce light in the cells of the body. They are human fireflies. Bioluminescence in fireflies and glow worms is drastically different from the luminescence generated by the indwelling Holy Spirit. The luminescence of the Holy Spirit is a natural light, it is not chemically generated. It is most evident when the cells of the body are free of spiritual and physical contaminants that can block the light of God.
When someone is free of sin (having cleansed their body and brain of every evil thought, word or action), and is seeking to live at the highest standards of righteousness, the cleansed cells become transparent. Thus, the light of the Holy Spirit in the solar plexus shines into and through all the cells and surrounds the body. The body appears as a ball of light when viewed in the spirit realm. Eventually, the light frequency increases to the point that it no longer is humanly visible in the spirit realm, although the person can be seen in the physical realm. They also can be seen in the heavenly realm. When God can see you in his ether, you truly are in the kingdom of God.