Upon the occupation of the possessed person's soul by the demons of Satan, his conscious mind would reject all positive emotions and desires, and approve only the negative emotions and desires of his heart in conformity with the will of Satan.
The more the conscious mind allows negative emotions and desires to be put into effect, the further away from God would be the possessed person, until he is either utterly destroyed by Satan, or experiences an epiphany that pulls him from the brink of hell.
As long as the demon-possessed person continues to do the will of Satan, he cannot love God with all his heart, and become a child of God (John 8:42-47). More than this, the Holy Spirit will not dwell in him, because he cannot understand the things that come from the Spirit (1st Corinthians 2:14).
On the other hand, if the demon-possessed person turns away from Satan by hearing, reading, speaking and practicing the gospel, the Holy Spirit would return and indwell him, and regenerate his soul.
If the demon-possessed person succeeds in inviting the Holy Spirit to dwell in his soul, the demons of Satan would be chased out, and God would instruct the Holy Spirit to reveal to the regenerated soul the things that come from the Spirit. On receiving the divine revelation, the regenerated soul would transmit it to the saved person's conscious mind.
The revelation from the regenerated soul would appear in the conscious mind as divine wisdom to enable it distinguish between truth and falsehood, right and wrong, with the result that the conscious mind would be empowered by the Holy Spirit to reject all negative emotions and desires of the heart, and approve only positive ones.
As the conscious mind continues to reject all negative emotions and desires sent to it, the heart would learn which emotions and desires the conscious mind would approve, and accordingly, send only positive emotions and desires for approval and implementation.
This ongoing interaction between the conscious mind and the heart would allow only positive emotions and desires to be put into effect by the body, until a time arrives when the heart would be transformed to initiate the rejection of negative emotions and desires without help from the conscious mind.
When the regenerated person's heart can reject negative emotions and desires on its own, he could then truthfully say he loves God with all his heart, and be justified to called himself a child of God.