Hey, great question. Thanks for asking, and welcome to the forum.
I think the best place to go for an answer to your question is to Matthew 12.43-45. We take this as parabolic, though. Jesus is telling a story to make a point about the hypocritical religious leaders. Jesus has turned the tables on his accusers. They accused him of casting out demons by the power of Satan, a charge Jesus strongly refutes. Here Jesus returns the indictment: they, not he, are the servants of the Accuser and Deceiver. Jesus’s point is that although he is casting out demons, this wicked generation is inviting all the more back in.
Just to let you know, I believe very strongly that a demon cannot enter a Christian for possession. The believer is God's temple, and neither Satan nor his minions have access there. I see no indication in Scripture that a Christian can be possessed. By the same token, there are enough references, along with plenty of testimony from missionaries and other Christians, that Satan can certainly
oppress believers (Mt. 16.23; 1 Pet. 5.8; James 4.7). To some extent, Satan makes it his business to oppress Christians and to deceive them.
I think it's quite fair to say that a person who has been a participant in the practice of witchcraft could certainly expect demonic attacks against them. Satan does not give up ground easily, and he will not just let a soul go without a fight (Eph. 6.10-18). We are engaged in a great spiritual battle, and the human soul is the battleground.
The Bible instructs us on how to guard against the demonic onslaught:
1. 1 Peter 5.6; James 4.7: "Humble yourself under God's might hand." Put yourself under his protection. Have you seen the 2005 Peter Jackson movie "King Kong"? About 2/3 of the way through the movie, a T-Rex is after the girl. Kong & the dino are fighting all the way down into the valley through a tangle of ropes. The girl lands right between Kong and the T-Rex. She's been afraid of Kong all along, but now stands between two giants. She decides to move over between Kong's feet. She realizes the T-Rex wants to destroy her but Kong wants to protect here. Put yourself under God's protection.
2. 1 Peter 5.7: "Cast all your anxiety on [God] because he cares for you. When we are under oppression, lean on the One who is legitimate strength in this situation.
3. 1 Peter 5.8: "be self-controlled and alert." Know what the Bible says about spiritual oppression, and know that God gives us victory against it (which doesn't mean that he keeps it away from us). There are plenty of Scriptures that are spiritual wisdom, strength, and protection against demonic oppression. Keep your head in the right place. God is our refuge and strength, a very present help in time of need.
About 10 years ago we let our dog outside before bedtime, and he must have smelled a shrew (a mouse-like rodent) in the tiger lilies, because his tail started wagging and he plunged into the flora. He pushed and snorted, pulled out and went around to the other side, pushed and snorted. He crashed through them. He dug in them. He went around and around. He sniffed and wagged. This must be where the expression “dogged persistence” came from.
I was standing near the perimeter, hoping that the shrew might make a dash for it, and I could call the dog to get him. After a half hour I had to pull him away so we could go to bed. He probably would not have quit. He would have snorted and dug and pushed and sniffed until he got his prey.
While he was digging my mind went to this verse (1 Pet. 5.8). Satan is hunting me, and so many others. With dogged persistence. Hunting, because he wanted the kill. And he would not quit. But as it turned out, the safest place for the shrew was right where he was: to find that place of safety and just stay there. For us, that place is in the arms of our Father. Just stay there.
4. 1 Peter 5.9; James 4.7; Eph. 6.10-18: "Resist the devil and he will flee from you." He is at work in your circumstances, in your heart, your mind, your mouth, and your actions. You have to resist temptation and your natural desires that are at work inside you.
I watched a documentary about a trainer of fighters. He said, "If you are trained in your mind not to break down and let the other fighter impose their will on you, you can turn the fight around at any time. … Nothing is ever as it seems to be."
Have no delusions about the reality of the powers of darkness or their hostility. But do not fear them. The God inside you terrifies them. They cannot touch you, let alone hurt you. But they can still seduce you, and they will try.
5. 1 Peter 5.9: "Stand firm in the faith." Purpose in your heart that you will not give in, you will not waver, that Satan has no control over you. Learn Scripture and quote it when temptation comes.
6. James 4.8; Ps. 27.1-5: "Draw near to God."
7. Meditate on God's word. I usually find a passage in the morning and meditate on it ALL DAY LONG. I roll it around in my head, thinking about different pieces of it, what it means, what it means for me. I go to bed still bathing in its richness.
Those are a few things that come to mind, from Scripture. Let's talk more as you want to.