The mechanism of how people can be possessed will be better understood using the analogy of ‘the fortress that is being attacked and surrounded’ in ancient times. The fort’s defense system includes the walls of the fort, archers, and food in the barn to wait for the enemy to come out. Enemies who besiege patiently will wait outside the fort, trying to weaken the fort by starving them or through the use of psychological tactics. However, it’s still fully spiritual, so perhaps you may want to clean yourself spiritually by hiring an expert to remove black magic from your body.
The enemy will pounce at every opportunity to find a leak in the fortress’s defense system. This whole process can take a lot of time. However, after the fortress has been broken through, the enemy will concentrate on expanding its exposure and then taking control of the fortress.
That is more or less the same way as ghosts (demons, and negative energy, etc.) possess a person and take control of that person. The victim can be seen as a fortress, while demands and negative energy can be seen as invaders.