Demon possession in the Bible

I was preparing for the Digital Sunday School lesson on Mark 5:1-20 about how Jesus frees the man possessed by the legion of demons. And while the main points are clear and wonderful - Jesus is the Son of God, he is so good he can overcome evil, and no-one is beyond the reach of Jesus - it does raise some hard to answer questions about demon possession or evil spirits. I’ve done my best to summarise answers to questions kids might ask here - this isn’t comprehensive but some key points. I’m using the language of demon possession here but in the lesson I talked about evil spirits living in the man; I’m using them interchangeably.

What is demon possession?

Yikes - what a question! So, as best as I can understand it, everybody in the world is under the influence of Satan, but thankfully, with the Holy Spirit’s help we can resist him. This influence come in the form of temptations and I’m sure he contributes to the brokenness of the world. However, there are many examples (in the Gospels particularly) of people who had demons living inside them. The effects are different for each person - including deafness and speechlessness, seizures, a lack of self-control and a propensity for self-harm, it’s all harmful, isolating and dangerous. While some of the symptoms of demon possession are disabilities or mental health problems, the gospel writers make a distinction between healing those whose illnesses (including those with the same symptoms) are a natural result of a broken world and those who have evil spirits in them.

Why do some people get demon possessed?

This isn’t a question the gospels answer other than to say that spiritual forces are real. I do just want to mention here that it’s not only evil spirits or demons who can live in people but if you ask him to the Holy Spirit, God himself, will live in you - and he is your surest defence against all evil (including your own).

Does it still happen today?

It definitely seems to be true that when God walked this earth as a human, Satan sent his demons into this world in a higher number than we’ve seen before or since. But we do see the early church dealing with them too (Acts 16 and 19) and Paul attributes the power of other gods to demons as well (1 Cor 10:20), so it doesn’t seem unreasonable to assume that they still exist on earth although they’re not as prevalent and possession by one rarer still. With Jesus you have nothing to fear from them though.
Our expectations should be set in line with the Bible and not with horror movies or medieval art. A part of that means we need to be careful not to diagnose demon possession where illnesses and mental health problems are the cause, nor to claim demon possession where people’s sinful hearts lead to harmful behaviour. Instead remember that our prayers, our love and reminders of God’s greater love will help in every situation.

How can the possessed be set free?

Jesus sets many people free, he is God and has all his goodness and power that no evil can stand against. This is as true for demon possession as it is for the power of sin to rule our hearts. Ask him for help and love as he loves - remember and remind “that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.”

Here’s a more in depth article I found helpful:
Miracles then and now - David Wenham for the Gospel Coalition

and here’s one specifically about the pig-incident in Mark 5:
Why did demons ask Jesus for Pigs? - John Piper on Desiring God