I would never tell anyone that they had a demon. Bottom line, because neither Jesus nor any of His apostles ever told anyone that they had a demon. When they ran across a demon that was manifesting itself in someone, they simply cast it out. If you tell someone they have a demon, or that you think they have a demon, which is the same thing, and cannot or do not cast it out, then you leave them with the initial burden of their problem plus the burden of now believing, if they believe you, that they have a demon.

Such a burden should never be put upon anyone. If you'll remember, Jesus cast a demon out of the little girl without being in her presence, and He also healed without being in the presence of the sick person. If He did it then He can certainly do it now. The point being, that believing prayer in the power of the name of Jesus Christ can do marvelous things for those who are ill, whether from a natural problem or from a demonic one, and whether you are in the presence of the ill person or not.

If your friend is a Christian, then regardless of the problems, God is working in them, as is stated in Philippians 1 and 2. Sometimes what we see in other Christians, and even in ourselves, is not demon activity but the flesh fighting against the work of God in them. That is to say, they are fighting against something that God wants them to do or wants them to stop doing; they are fighting to do their will instead of God's will. The flesh is a terrible thing and gives us far more trouble than any demons.

Jesus said to His disciples just before He went to Calvary, that the enemy had come but he found nothing in Him and therefore he could do nothing to Him. The principal being that the enemy can only do to us according to what he can find in us; that is, what he can find in us that belongs to him or what we have in common with him. So as God works in us more and more, the enemy can do less and less to us. That being true, we should concentrate on drawing closer to God, on cooperating with the work He is doing in us, and in doing His will whenever we know it.

Although all this may not sound like advice or suggestions on what you should do in relation to your friend, there is much in it that will help you to decide what to do or not to do.

God bless.