D&C 50
“I say it that ye may chase darkness from among you” (verse 25 emphasis added).
What motivation – all things are subject unto him that is ordained of God and to be ordained of God you must be cleansed from all sin. Then you can ask whatsoever you will in the name of Christ and receive it because all things are subject to you, like Nephi in Helaman 10. For those who have not achieved that yet (everyone) be aware that it shall be given you what to ask, for if ye are cleansed from all sin ye will follow the true order of prayer which will keep your desires in line with the will of your God and you shall receive knowledge of the blessings which he is anxious to give you.
If we encounter a spirit that we do not understand we should ask in prayer and if that same spirit is manifest then it is of God, otherwise it is not and should be declared as not of God.