The ritual of exorcism is not practiced by an ordinary priest. An exorcist requires specific training and must be thought to have a personal sanctity. He can be exposed to dangerous behavior and personal threat. His prayers often cause a violent response as he attempts to shine a beam of light into the darkness.
Satan is pure spirit. He often appears as something else, to mislead. He appeared to Padre Pio as Jesus, to frighten him. He sometimes appears as a raging animal.
When I am told (by those who confuse predestination with God's providence) that God already knows who will be saved and who will be damned, and therefore anything we do is useless, I usually answer with four truths that the bible spells out for us:God wants that everyone be saved; No one is predestined to go to hell; Jesus died for everyone; and everyone is given sufficient graces for salvation.