The simplest explanation for The Seventh Day would be ‘The Exorcist’ meets Training Day’. Father Peter Costello, portrayed by Guy Pearce, is a jaded and experienced priest who operates outside established protocols. Father Daniel García (Vadhir Derbez) represents a young, idealistic graduate from the seminary forced to discard his textbook knowledge of exorcism. They work together in the city, functioning almost like 'undercover priests', and occasionally deliver some forceful justice on behalf of their faith. The premise is full of opportunities for humor—it brought Monty Python’s Bishop sketch to mind—and it's disappointing that writer/director Justin P. Lange treats the story with such solemnity. It seems a real oversight that there isn’t a scene where Costello and Garcia engage in a humorous dynamic, playing off each other as a good priest and a bad one during an exorcism, or one where the archbishop (Stephen Lang) demands to see their religious texts and equipment and removes them from the case. Furthermore, Lange demonstrates a lack of understanding regarding the subject matter he’s exploring. If the devil's greatest deception is making people believe he doesn't exist, here he employs an even more clever tactic: concealing himself in the minds of those who perform exorcisms. A little research would have revealed that “If Satan drives out Satan, he is divided against himself. How then shall his kingdom stand?” (Matthew 12:26). The standard procedure involves the devil placing demons within individuals, but how could a supposed expert maintain their facade without occasionally expelling some of his own demonic forces?

Source on TMDB