The people of Malta believed that justice was a personal power or a god who punished criminals. When nothing bad happened to Paul, they changed their minds. They saw that he was not harmed by the snake. So they thought he had power over snakes and said that he must be a god (compare 14:11–12).
But this was not true. Paul did not have special power in himself. Instead, his survival showed that God was protecting him (compare Mark 16:17–18).