[Serious] Why defecation?

[John 6IX Breezy]

LOL Animals shy away from water with shit it in when they possibly can. Maybe it's a religious thing with them.

You are more or less correct on both accounts. Disgust is part of what's known as the "Behavioral Immune System." Pathogens are not evenly distributed throughout the environment; they are often localized in specific regions (e.g. feces). Disgust prevents disease through contact-avoidance, meaning you avoid ingesting, touching, or coming close to the contaminated object. But again, its a species-specific response; you and most animals might stay far away from the odor of a rotting corpse, but a vulture isn't disgusted by it and might even find it pleasurable.

There is definitely a lot of religious symbolism to purity and impurity.