Can a Christian have a demon ?

Range of manifestations and control

Evil spirits can and do inhabit people. That much is obvious from the Bible, and from the experiences of many cultures.
The Bible describes different levels of control over those that are hosts to these demonic spirits.
From the subtle manifestations over the fortune teller in Philippi (Acts 16:16-18), to the more obvious work of throwing a boy into fire and causing him to convulse and foam at the mouth (Mark 9:20-22).

The question of whether a Christian can be inhabited by a demon is an important one to answer. Like all matters of truth, it "helps us to co-operate with reality". 

Or more specifically, it lets us know how to deal with different issues that Christians experience in their walk and in their quest to grow in sanctification.

Disciples of Christ long to grow in sanctification, they hunger to be more like Him. When they've been struggling with a sin for sometime without any real victory and someone says that a resident demon is causing it, an exorcism doctrine can offer a promise of quick victory. 

But it also offers the temptation of transferring responsibility to another quarter ( an implicit "the devil made me do it")

A born again believer that goes through an exorcism to deal with a problem with the flesh can really add to his own woes:
1. He still has his original problem, the flesh, that hasn't been dealt with
2. He now believes that he has a demon
3. He also believes that no one can deliver him from the demon.

In the case where he was having a genuine spiritual conflict, he's now using the wrong response to fight a battle on the wrong front.

Demons inhabit houses

 
Jesus described what happens when a demon is cast out of a person:

"When the unclean spirit has gone out of a person, it passes through waterless places seeking rest, but finds none. Then it says, 'I will return to my house from which I came.' And when it comes, it finds the house empty, swept, and put in order. Then it goes and brings with it seven other spirits more evil than itself, and they enter and dwell there, and the last state of that person is worse than the first. So also will it be with this evil generation." (Matthew 12:43-45)

In the context of casting demons out of people, Jesus taught a principle - He said that:

"no one can enter a strong man's house and plunder his goods, unless he first binds the strong man. Then indeed he may plunder his house." (Mark 3:27)

If I walked into your home, picked up your tv and started walking out with it while you were watching me, I would be sure to have a difficult time of it.
But if I first tied you up, then I'd have the leisure to take anything I wanted, even make myself a nice chicken dinner before walking out.

Jesus taught that He would live in us (John 14:23), and later Paul affirmed: "Do you not know that you are God's temple and that God's Spirit dwells in you?" (1 Cor 3:16)

If we take scripture as authoritative we have to concede 2 things:
firstly, that Jesus is the strong man living in our houses and
secondly, that an evil spirit will first have to tie Him up before it can "plunder His goods". 

- not likely!

Everything we need

 
God has given us everything we need for life and godliness (2 Peter 1:3-4), and Jesus asked that the Father would sanctify us by His Word (John 17:17).
If we needed some kind of exorcism in order to progress in the spiritual life, He would have shown us this in His Word.
In fact, you won't find one instance in scripture where a born again believer has a demon cast out of him, nor will you find any teaching that encourages the practice.

Corinth - Sin City

If any book in the Bible would have given us instructions regarding this, it would have been Paul's writings to the Corinthians.
Among the pagan world, Corinth had a reputation of debauchery. People would fornicate with temple prostitutes as worship to their pagan god.
This even had an influence in the church, where a man in the assembly was fornicating with his father's wife!

With all these demonic influences in their culture (and they would have participated before hearing the Gospel), their isn't even a hint of their need for exorcisms.
Paul keeps exhorting them to "flee from sexual immorality" (1 Cor 6:18), to "be watchful, stand firm in the faith, act like men, be strong." (1Cor 16:13), and even to " Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?-unless indeed you fail to meet the test!" (2 Cor 13:5)

What about experience?

It first needs to be stressed that the Word is a lamp to our feet and a light to our path (Psa 119:105)
Navigating amongst spiritual realities takes supernatural light, the natural light of our experiences can cause us to stumble and fall into a ditch - or worse.

The devil has motivation for us to expend our energies in the wrong place.

Sometimes believers have strong spiritual conflicts with demonic spirits. They should submit to God, resist those spirits and they will flee (James 4;7). Running to a spiritual guru and going through a ritual is just not biblical!

At other times people in the church quite obviously manifest demonic possession.
They are sometimes held up as 'proof' that a Christian can be inhabited by a demon, but not everyone that calls Jesus Lord belongs to Him (Matthew 7:21-23).

Conclusion

We need to understand this issue clearly so that we can grow in our sanctification, take responsibility for our own sins, and do effective spiritual warfare against the devil.
We need to rid ourselves of these new theological fashions, so that we know how to pray for and minister to those in need.