What is Paul’s thorn in the flesh, explained by apologist John MacArthur
There are a dozen ways of interpreting apostle Paul’s thorn in the flesh, but the most popular interpretation is that the thorn was a physical ailment that he had to suffer.
However, leading apologist John MacArthur sees it as a literal person, not some form of weakness, disability, or whatnot.
God sent an Angelos (ἄγγελος), which is a messenger of Satan in the case of people. It is most likely a false teacher possed by a demon to torment Paul.
Humble messenger of God
Many times, God allows the enemy to wreak havoc in our lives to test our faith or humble us. It’s not because we’re too proud but because we may become one and depend on what we know rather than Christ alone. [Divine affliction]
In the case of Paul, tearing and challenging his mission in Corinth was necessary to stop Paul from being conceited, according to MacArthur. After all, the revelations of Jesus unique to him may cause pride, which is the secret sin of many pastors.
To test our faith or humble us.
Paul’s thorn in the flesh is the devil. The devil would shake up and stir up and confuse the brethren. Look at what Paul wrote in the context of the big picture.
2nd Cor 12: And lest I should be exalted above measure through the abundance of the revelations, there was given to me a thorn in the flesh, —>the messenger of Satan to buffet me, <—lest I should be exalted above measure.
 For this thing I besought the Lord thrice, that it might depart from me.
 And he said unto me, My grace is sufficient for thee: for my strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me.
 Therefore I take pleasure in infirmities, in reproaches, in necessities, in persecutions, in distresses for Christ's sake: for when I am weak, then am I strong.
Paul reassures us the thorn on the flesh is the devil again in Galatians 3.
Galatians 3:1] O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you?
 This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith?
 Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?
 Have ye suffered so many things in vain? if it be yet in vain.
Galatians 4:15] Where is then the blessedness ye spake of? for I bear you record, that, if it had been possible, ye would have plucked out your own eyes, and have given them to me.
 Am I therefore become your enemy, because I tell you the truth?
The devil was giving Paul a rough time because he did not want his gospel to be known and was stirring up the pot by sending false teachers and ministers leaving the church in a mess just like it is today one big mess because of sin. As all sin is of the devil 1st John 3:8. All sinners will burn Christian sinner or not.
2nd Cor 11:12] But what I do, that I will do, that I may cut off occasion from them which desire occasion; that wherein they glory, they may be found even as we.
 For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ.
 And no marvel; for Satan himself is transformed into an angel of light.
 Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.
Sin would not be around if there are no sinners. I am an ex-sinner saved by grace Romans 6:18.