What is Deliverance?
Deliverance is God's manifested power (the miraculous) to free Believers from the bondages of sin and curses that were inherited through the generational blood line. The bible calls Deliverance "the children's bread."
There are many reasons why there is demonic bondage in the lives of the Believers. Demonic oppresion enters when there is unconfessed sin or what we call Open Doors. Demons are also present due to unconfessed sin in the past family generations called "curses." Both of these entry points give demons legal rights to cause havoc such as sickness, disease, failures, and poverty in the lives of the Believers.
The main reason many Christians do not find reprieve for their situations even after praying and fasting is because the root issue of what they have been dealing with was never plucked out (or cast out).