In my many years of studying Jesus and His works and ministering to the broken, the lost and the afflicted (spiritually and physically) in His name, I have come to the conclusion that the enemy (devil) can only enter a person in four ways.
I receive phone calls almost every day from those seeking spiritual warfare or deliverance prayers for themselves or someone else. I have written several books on the subject but it always breaks down to four ways that they received affliction from the enemy.