I wasted an hour and fifty-two minutes of my life watching this movie. I would not recommend this movie to anyone, especially not to anyone who subscribes to the Judeo-Christian faith.
Despite his reluctance, the priest, filled with purpose and conviction, enters the house to perform the exorcism, and he was able to gain control over the situation through the power of God on Whom he called. Yet, somehow, the entity was able to exert its will and take the life of the priest, even though the priest, at no point, wavered or lapsed. Utter nonsense. But I shouldn't be surprised; this is a Hollywood production, after all.