Prayer: "Communication with God or (for some traditions) other supernatural beings and departed spirits. There are many forms of prayer, including propitiation, adoration and thanksgiving, but most philosophical discussions of prayer have focused on the problems posed by petitionary prayer, in which a person makes a request to God for some specific good. These problems include such questions as the following: Do such prayers require special divine actions (sometimes called "interventions," though the term is misleading) in the world? Can a God who is 'omniscient and perfectly 'good be affected by human prayers? The solutions to such questions require thought as to why a good God would wish to employ the free actions of humans in the pursuit of his goals."
Evans, C. (2002) Pocket Dictionary of Apologetics & Philosophy of Religion. Downers Grove, IL: InterVarsity Press.