In "The Rime of the Ancient Mariner," a superstitious belief holds most sailors back from killing the albatross, because they believe the act will bring bad luck. When the Mariner disregards that superstition, horrors befall the sailors.
Superstitions can thus stand in for deeper, truer beliefs. I can be argued that the real reason the Mariner and crew are punished for the death of the albatross is not because the Mariner violated a superstition. Rather, because the Mariner does not understand that the albatross is a beloved creature formed by God and worthy of being cherished and protected. Until he sees and blesses the water snakes, the Mariner does not understand that nature is a living manifestation of God and as such is blessed and should be blessed.
The poem ultimately suggests that it is best for people to understand and adhere to the true meanings behind what seem like mere superstitions. The point of the poem is not to convey that it is bad luck to kill an albatross but to suggest, at a deeper level, why it is bad luck—killing an innocent creature for no reason indicates a disrespectful attitude towards God and His creation. Superstitions can protect people, the poem suggests, from violating God's law.