What is the effect and purpose of the man using prayer as he engages in a debate with the police officer? consider the man's audience as well as the presence of cameras and journalists

The man uses prayer to show the cameras and journalists present how African Americans at the time were oppressed by white Americans. By praying instead of reacting with anger, the man's actions elevate the moral purpose of the civil rights movement and show that the police are acting as oppressors, thereby, preventing the policemen from using physical force. The man hopes to evoke sympathy and a reaction from the audience so that more people join the fight for civil rights. He achieves what he is attempting to do as he is arrested and the officers are made to look despotic. The use of prayer highlights the strategy of the SCLC to use nonviolence, reason, and morality in their struggle. (from plato)

Because writing on paper is said to engrave what your writing down into your brain therefore writing your thoughts is better than speaking them.