Humans are always vulnerable to evil and we can see that this statement is true with examples from The Pearl. There are a certain characters being defenseless in front of the power of evil.
Kino’s son Coyotito was stung by a scorpion in the beginning of the story and with his wife, Juana, they went to the doctor in the town to heal his son. The doctor was vulnerable in front of the evilness of discrimination and money. He was against Kino’s race and he refused to cure Coyotito when he heard that they were Indians, saying “Have I not have anything better to do than cure insect bites for “Little Indians”?” Then the doctor considered about whether they have any money: he sent the servant to ask about the fee needed for treatment but obviously Kino didn’t have enough money so the doctor pretended that he wasn’t at home and sent Kino away. He was supposed to be saving people’s life and that is the responsibility of a doctor but he was defeated by the evil in his mind.
Then, Kino wanted to gain wealth and a higher social status with the great pearl he found so that he can have a better life and end poverty and ignorance by sending Coyotito to school with the money he will make. However, he was vulnerable in front of his ambition and greed. His greed to the demand for wealth and a higher social status transformed him from a loving man to a mad one. He had a contented life living with his family at first, but the pearl brought him ambition and he insisted to have it sold at a high price. All that he could see was the desire in making money out of the pearl but Juana can also see what the family is losing. She tried to persuade Kino to throw the pearl away or destroy it but Kino was already powerless in front of the evil the pearl brought--ambition and greed so that he even beat Juana in order to protect the pearl. He was vulnerable in front of evil and lost his mind, protecting something that brought sin to him than the woman he loved most.
Moreover, the pearl further transformed Kino to a savage criminal. He killed a man in the dark, without even knowing who the man was, just because he wanted to protect the pearl. Then he had to leave the place he was familiar with to escape, and trackers wanted to kill him for the pearl. Being controlled by the evil brought by the earl, Kino wasn’t willing to give up the pearl even for himself and his family’s life. Humans are so weak in front of evil and had to sacrifice their life, their time, family and even their dignity for it.
So, as to conclude from the above examples, humans are vulnerable to evil.