Why do all kinds of monsters in the Journey to the West have to perform rituals before eating Tang Priest?

In the Journey to the West, the monster caught the Tang Priest, instead of eating it immediately, he tied it up first. They either bathe the Tang Priest or light a container first. A strong sense of ceremony. I think there are two reasons.

First, the original novels and TV plays of Journey to the West are all works of art, which are different from reality. If in reality, the monster catches the Tang Priest, he may take it back to the abode of fairies and immortals and eat it directly. After all, eating Tang monk meat can live forever. Who can wait that long? But in works of art, it can't be expressed like that. To put it bluntly, if every monster directly catches Tang Yan and eats him, there will be no follow-up, and Tang Yan will die!

The second is a deeper interpretation. Tang Priest had to go through eighty-one hardships, none of them, and so many hardships were arranged by Bodhisattva to make him complete. Since there is such a premise, let's think about it. Will Tang Priest really die? It's impossible. The monster is just a character in the "81 difficulty", and he can't eat the meat of Tang monks. It's ok to dress up in a ceremony! So in any case, Tang Priest will be in danger for various reasons.