Those who have been enslaved to something for a very long time will find it very difficult to imagine what a life of freedom without that thing is like.
Mind, freedom is undoubtedly something we all idealize and want. But what freedom is like, and how I live in it, is hard to imagine until I have it.
People enslaved to sin (even believers who have been in that condition) will not immediately have good freedom lives and habits when they have renounced slavery or been liberated. It will take time to explore the new land they are in and figure out how to live in it.
Building new habits can be so hard that returning to slavery, the known, can seem appealing.
This is part of the work of discipleship and why it takes time. Conversion without discipleship is akin to freeing slaves but not offering any help on the morning after their freedom is announced.