Both of these characters are so unsympathetically portrayed that they function only on a symbolic level. The doctor is the representative of another way of life — a way of life connected with the pearl buyers and with foreign elements. He has no redeeming qualities, and his actions show him to be the most despicable, heartless individual that one could encounter.
The mere mention of his name among the villagers creates an aura of fear and awe. He has never made an appearance in the village. Thus, later when he does come to see Coyotito, it is with utmost suspicion that Kino allows him to see his son.
When we first meet the doctor, it is in a rather decadent setting. He is lounging in a silk robe and is being served chocolate on a silver service amidst lush flowers. He is dreaming of a woman with whom he once lived in Paris. Everything about him suggests a person who over-indulges himself and cares nothing about the welfare of anyone else. For example, the contrast between Kino's simple breakfast and the opulence of the doctor's breakfast is one more parallel to contrast the two human beings.
While it is not explicitly stated, the doctor, when he attends Coyotito, obviously gives the baby something that will make him sick enough so that the doctor can return in one hour and pretend to cure the baby of the scorpion bite. Steinbeck has already let us know that the seaweed poultice that Juana applied has taken care of the bite; therefore, the doctor's actions are only acts of inhumanity — acts that totally contradict the ethics of his profession. He then tries slyly to get Kino to give him the pearl for safekeeping; only then is the full extent of the doctor's greed and evil apparent. Using his authorial voice, Steinbeck has the beggars speak of the doctor's character. They knew of "his ignorance, his cruelty, his avarice, his appetites, his sins, his clumsy abortions and the little brown pennies he gave sparingly for alms. They had seen his corpses go into the church." The doctor, then, represents in this novel all of the evil forces working against Kino.
The priest, while not presented as being as evil as the doctor, is shown to be a person not really concerned about the spiritual wellbeing of his parishioners. He is more a representative of the rich than he is a representative of the church. He has a sermon that he preaches yearly, and the central message of the sermon, with examples, is that all people who are trying to improve themselves are sinning against God because they refuse to accept the station in life that God has assigned to them. When the priest first hears of the great pearl, he does not even know who Kino is; he wonders if he married Kino and Juana, and then he immediately thinks of all the repairs which the church needs and which it can have if he can get Kino's pearl. His visits to the village are so rare that everyone in the village knows why he comes to visit Kino.
Given the qualities of the priest, it ultimately becomes ironic that Kino wants to sell the pearl so that he can use the money to be married to Juana in the church and so that Coyotito can be baptized here.