There are people who might need deliverance even though they have become Christians. This is especially important where they were dedicated to the devil (through Satanic altars) before they came to know the Lord; this often happens when people dabble into the occult.
People may also need deliverance because of a generational curse. This is where their ancestors made covenants on their behalf with an agent of the devil. This would be the case if any of their 2 parents, 4 grandparents, 8 great grandparents or 16 great-great grandparents went into the occult or practised sorcery or divination or consulted mediums or witch doctors or were involved in witchcraft at any time in their lives. I have gone as far back as great-great grandparents because the effect of generational curses can last up to the fourth generation! The Bible says in Exodus 20:5(KJV) “Thou shalt not bow down thyself to them, nor serve them: for I the Lord thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me.” [My emphasis.]
Our ancestors sinned, but they have died—and we are suffering the punishment they deserved!
If there are negative traits which you noticed in your parents, which you hated such as alcoholism, anger, child abuse, adultery, wife abuse etc and which you can now see in your own life, then you need to be set free! Also, if you notice a pattern of things in your family among your siblings or other family members, such as alcoholism, suicide, anger, adultery, miscarriage, divorce, not getting married until a certain, getting divorced at a certain time, not having children until a certain time, etc then you need to seek help.
These things won't go away simply because you're now born again! They need to be dealt with! In the same way that you can be saved and be poor unless you apply the Biblical principles for prosperity, you can be saved and be under the devil's yoke of oppression! There are principles laid out by God in the Bible which need to be applied for you to enjoy true freedom in Christ.
If any of these things apply to you, ask a pastor with insight into spiritual warfare to pray for you. Jesus will set you free. I am also available to minster to anyone who is in need of deliverance.