The double mindedness mentioned specifically by James is also found in Jesus when he speaks of serving loving God or mammon. Paul warns us to not quench the Holy Spirit, but believers as I see it do it [quench the Holy Spirit] altogether too regularly which also then alludes to the double mindedness. The fruit we bear depends upon who we are serving at the moment. For a time God is allowing the double mindedness, but in the end of the matter a person must finally go one way or the other.
"And if it seem evil unto you to serve the LORD, choose you this day whom ye will serve; whether the gods which your fathers served that were on the other side of the flood, or the gods of the Amorites, in whose land ye dwell: but as for me and my house, we will serve the LORD." Joshua 24:15
God has through Jesus opened up new possibilities bypassing the prophet and priest as seen in the OT especially among the offspring of Jacob/Israel. The Love is directly available now to anyone who sees the Light and walks toward it. Church groups can and do too often interfere with the better possibilities by teaching people to quench rather than to yield to the Holy Spirit. A person walking alone outside of organized church groups is, of course, able to do the same thing especially when drawn by the lust of the flesh, the lust of the eyes and/or the pride of life.
This could be a person never really born from above [born again] or it could be one who simply has quenched the Spirit so much and so often that the old man within has regained at least in a measure the dominion which could have or should have been gone or on its way out. Every baby in Christ must grow toward God. Failure to do so could be worse than the death from whence the child came...
"When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest, and findeth none.
Then he saith, I will return into my house from whence I came out; and when he is come, he findeth it empty, swept, and garnished.
Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation." Matt 12:43-45
Yes, but some have traveled so far in the wrong direction that they cannot tell if the fruit is good or evil:
"Woe unto them that call evil good, and good evil; that put darkness for light, and light for darkness; that put bitter for sweet, and sweet for bitter!" Isaiah 5:20
There is love indeed and there are others kinds of love. Sometimes using the word you did, agape, may help someone understand that are differences in a discussion.
We are to love our wives and we come together with our wives physically to consummate the marriage and to confirm our love for one another...
While we are to love our neighbors also, we are Not to consummate that love with them in the same way because that would be adultery. We need to encounter and practice the difference. We need God's help us do that. Being able to explain it words is certainly not good enough!
I guess I have not really looked much into what a doctrine of demons is. To me getting into the Way of God and staying there always should take care of anything demonic.
The thing we need to avoid is deceptions in our walk as we are walking with God. Who can be deceived? Anyone who falters or otherwise moves away from or loses his love for the Truth! In that deception or as Paul names it, delusion, probably we will find among other things any doctrines of demons.
So then therein, in such delusions, we may encounter the reasons why people who are supposed to be part of God's Church are too often found rather engaged in the worst kinds of ungodly activities.
Taking our eyes off of Jesus for even a moment can get us into serious trouble with God and hurt other people.
Give God the glory!