When a person becomes a child of God through faith in Jesus and the Holy Spirit then fills them, it brings about new life. At the beginning it's very typical for the change in a person to be evident but as time goes on the old life, from which they were delivered, begins to creep back in. Many fall back into their old life and leave Jesus behind but that's not the plan or will of God for a person rather it's to grow in grace and humility all the while seeing the power of God moving in and through us keeping us on the right track.