The character names just don't make sense?
So every neon brought to heaven is named after a color, we obviously know of neon white, neon yellow, etc. and have heard of neon orange and neon smoke too, using this I assume that every neon is named after a color. This would be fine if it was just code names given to them by the believers, but we see in flashbacks that they are referred to by the color names. This would also be fine if the group they were in just had codenames for everyone based off of colors, but why would everyone else in heaven who most likely isn't affiliated with the group be named after a color as well?
This leads me to two theories:
The group white was a part of has code names for everyone based off of colors, and everyone brought to heaven as a neon happened to be part of that group.
Everyone in this world is named after a color and the believers just picked the strongest person for each color.