A thorn in the flesh

"And lest I should be exalted above measure by the abundance of the revelations, a thorn in the flesh was given to me, a messenger of Satan to buffet me, lest I be exalted above measure." 2 Corinthians 12.7

The Work of God, or the destruction of the works of satan, demands total selflessness. And the greater the revelations of the Spirit, more humility is required. It is not known exactly what kind of thorn in the flesh Paul had. But surely, God allowed him to stay protected from pride.

ANOINTING

"Thus Esau despised his birthright."       Genesis 25:34

Adam rejected God's anointing, Esau rejected Isaac's anointing, Judas Iscariot rejected Jesus' anointing and the same spirit of rebelliousness has continued to be passed on from generation to generation. 
Those who turn their backs on the anointing of the Divine are subject to Satan's power. You can't have God as your Lord and the devil as your lord at the same time. You are either a child of God or a child of the devil. You are either a temple of the Holy Spirit or a vessel of the devil.
This is why most believers are troubled, unsuccessful and possessed by demons. They have accepted Jesus as their Savior but have rejected Him as their Lord.