Exorcism
In Catholic Christianity, exorcisms are performed in the name of Jesus Christ. A distinction is made between a formal exorcism, which can only be conducted by a priest during a baptism or with the permission of a bishop, and "prayers of deliverance" which can be said by anyone.
The Catholic rite for a formal exorcism, called a "Major Exorcism", is given in Section 11 of the Rituale Romanum. The Ritual lists guidelines for conducting an exorcism, and for determining when a formal exorcism is required. Priests are instructed to carefully determine that the nature of the affliction is not actually a psychological or physical illness before proceeding.
Exorcism
From the 16th century onward, Lutheran pastoral handbooks describe the primary symptoms of demonic possession to be knowledge of secret things, knowledge of languages one has never learned, and supernatural strength. Before conducting a major exorcism, Lutheran liturgical texts state that a physician be consulted in order to rule out any medical or psychiatric illness. The rite of exorcism centers chiefly around driving out demons "with prayers and contempt" and includes the Apostle's Creed and Our Father.