Why might Parris refer to Reverend Hale as Mr. Hale?

Reverend Samuel Parris is not well-liked in the community of Salem, despite his position as their spiritual leader. Consequently, he is insecure. His insecurity drives him to try to exert more power and authority to compensate. Although he is responsible for inviting Reverend Hale to Salem to get to the bottom of what is plaguing the girls, his insecurity deepens when Hale arrives and takes charge of what should really be Parris's responsibilities. It is reasonable to think that Parris mistakenly thought that he would look like a wise leader for bringing in an expert consultant, but instead, he looks like a panicked and fearful weakling quickly relegated to the the sidelines. Reverend Hale has a reputation for being a witchcraft expert, and Parris quickly comes to view him as a rival. In calling him "Mr." instead of "Reverend," Parris is trying to downplay his rival's strength.