remember that the entire goal of the Devil in the Exorcist, was to possess Father Damian Karas just long enough to make him commit suicide. You must never allow your aura to become weak in these times. you must not let your will power become weak. fasting, seriously consider mortification of the flesh when you feel you are under demonic attack.

also, Damian Karas ALLOWED the demon to enter him, Satan used his love and sympathy for the little girl's suffering to let the demon invade him. That is a sacrifice Jesus Christ NEVER made for anyone, nor would he ever. You don't make Satan weaker by letting him take your lives.