This is awesome. I think you did an excellent good job in explaining the nuances of the emotion (i.e the overall negative perceptions of it in society based on the viewpoints of religion and how it can change within the individual over time).

As you discussed, though envy is generally seen in a negative light, there are adaptive benefits to the emotion as well.

I took a "psychology of emotions and motivation" course as a part of my psychology degree which really helped me understand emotions. Overall, emotions are adaptive in humans and they often serve a social function. They communicate feelings to others, influence how others interact with us, they facilitate social interaction and they help us create, maintain and dissolve relationships. As such, emotions in humans are not random psychological and biological events that have no meaning. To the contrary, each emotion serves a very specific function in the individual.

Envy is a cognitively complex emotion that is influenced by social mechanisms.

On a basic level, envy's adaptive function is to motivate the individual to improve their social position to that of the person that is envied. As such, it can motivate individuals to improve themselves which can be very positive for the individual and society in general.

However, as you also suggested, envy can also have a more destructive aspect to it which is sometimes referred to as "malicious envy." Malicious envy can motivate the individual to sabotage or "pull down" the envied person to an inferior level.

According to some researchers, the difference in how envy functions within the individual comes down to an evaluation of deserved-ness. If the individual believes that the other person earned their superior position and they deserve it, then that mindset can lead the individual to believe that the world is a fair and just and that improvement of the self is possible. This can motivate the individual to work harder in order to improve themselves as well. On the other hand, if the individual believes that the envied person's superior position is not deserved and that it was obtained through an unfair advantage, then this can lead to the belief that the world is not fair and just and that self improvement is not possible, which in turn can manifest malicious envy within the individual.

As you pointed out with your demonstration of where the emotion manifests within the brain a person biology interacts with their psychological and social environment.

Anyway, that's enough of my rambling. As always, great article!

Reference: Reeve, J. (2016). Understanding Motivation and Emotion (6th ed.). Hoboken, NJ: Wiley