Prayer plays a significant role among many believers. Muslims believe that the purpose of existence is to worship God. He is viewed as a personal God and there are no intermediaries, such as clergy, to contact God. Prayer often also includes supplication and asking forgiveness. God is often believed to be forgiving. For example, a hadith states God would replace a sinless people with one who sinned but still asked repentance. Christian theologian Alister McGrath writes that there are good reasons to suggest that a "personal god" is integral to the Christian outlook, but that one has to understand it is an analogy. "To say that God is like a person is to affirm the divine ability and willingness to relate to others. This does not imply that God is human, or located at a specific point in the universe."