Of course dabbling in the occult is a reason for some being possessed.
Clearly ... as Jesus said ...practicing sin ... or being unclean of heart allows Satan ownership of an unclean vessel.
If sin is rebellion towards God then rebellion will lead to an unclean heart.
I don't think it's a coincidence ... that
Mark 7 begins with Jesus teaching on what it means to be unclean and moves to him casting out an unclean spirit in a young child.
Mark 7
Clean and Unclean
1The Pharisees and some of the teachers of the law who had come from Jerusalem gathered around Jesus and 2saw some of his disciples eating food with hands that were "unclean," that is, unwashed. 3(The Pharisees and all the Jews do not eat unless they give their hands a ceremonial washing, holding to the tradition of the elders. 4When they come from the marketplace they do not eat unless they wash. And they observe many other traditions, such as the washing of cups, pitchers and kettles.[
a])
5So the Pharisees and teachers of the law asked Jesus, "
Why don't your disciples live according to the tradition of the elders instead of eating their food with 'unclean' hands?"
6He replied, "Isaiah was right when he prophesied about you hypocrites; as it is written:
" 'These people honor me with their lips,
but their hearts are far from me.
7They worship me in vain;
their teachings are but rules taught by men.'[
b] 8You have let go of the commands of God and are holding on to the traditions of men."
9And he said to them: "You have a fine way of setting aside the commands of God in order to observe[
c] your own traditions! 10For Moses said, 'Honor your father and your mother,'[
d] and, 'Anyone who curses his father or mother must be put to death.'[
e] 11But you say that if a man says to his father or mother: 'Whatever help you might otherwise have received from me is Corban' (that is, a gift devoted to God), 12then you no longer let him do anything for his father or mother. 13Thus you nullify the word of God by your tradition that you have handed down. And you do many things like that."
14Again Jesus called the crowd to him and said, "Listen to me, everyone, and understand this. 15Nothing outside a man can make him 'unclean' by going into him. Rather, it is what comes out of a man that makes him 'unclean.' "[f]
17After he had left the crowd and entered the house, his disciples asked him about this parable. 18"Are you so dull?" he asked.
"Don't you see that nothing that enters a man from the outside can make him 'unclean'? 19For it doesn't go into his heart but into his stomach, and then out of his body." (In saying this, Jesus declared all foods "clean.")
20He went on: "What comes out of a man is what makes him 'unclean.' 21For from within, out of men's hearts, come evil thoughts, sexual immorality, theft, murder, adultery, 22greed, malice, deceit, lewdness, envy, slander, arrogance and folly. 23All these evils come from inside and make a man 'unclean.' "
The Faith of a Syrophoenician Woman
24Jesus left that place and went to the vicinity of Tyre.[
g] He entered a house and did not want anyone to know it; yet he could not keep his presence secret.
25In fact, as soon as she heard about him, a woman whose little daughter was possessed by an evil [unclean, in the Greek] [h] spirit came and fell at his feet. 26The woman was a Greek, born in Syrian Phoenicia. She begged Jesus to drive the demon out of her daughter.
27"First let the children eat all they want," he told her, "for it is not right to take the children's bread and toss it to their dogs."
28"Yes, Lord," she replied, "but even the dogs under the table eat the children's crumbs."
29Then he told her, "For such a reply, you may go; the demon has left your daughter."
30She went home and found her child lying on the bed,
and the demon gone.
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Makes you wonder if it was Mom's uncleaniness/sin in her heart that resulted in her young child being possessed??? Something to dwell on....