Multiple interpretations exist, most of which have very little scriptural basis.
2 Corinthians 12
1It is not expedient for me doubtless to glory. I will come to visions and revelations of the Lord.
2I knew a man in Christ above fourteen years ago, (whether in the body, I cannot tell; or whether out of the body, I cannot tell: God knoweth;) such an one caught up to the third heaven.
3And I knew such a man, (whether in the body, or out of the body, I cannot tell: God knoweth;)
4How that he was caught up into paradise, and heard unspeakable words, which it is not lawful for a man to utter.
5Of such an one will I glory: yet of myself I will not glory, but in mine infirmities.
6For though I would desire to glory, I shall not be a fool; for I will say the truth: but now I forbear, lest any man should think of me above that which he seeth me to be, or that he heareth of me.
7And 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.
8For this thing I besought the Lord thrice, that it might depart from me.
9And 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.
10Therefore 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.
11I am become a fool in glorying; ye have compelled me: for I ought to have been commended of you: for in nothing am I behind the very chiefest apostles, though I be nothing.
I would like to point out the word buffet in verse 7. Greek interpretation inludes the phrase “to strike blow after blow”. Other places this same word occurs in the New Testament are
64Ye have heard the blasphemy: what think ye? And they all condemned him to be guilty of death.
65And some began to spit on him, and to cover his face, and to buffet him, and to say unto him, Prophesy: and the servants did strike him with the palms of their hands.
1 Peter 2:19-21
19For this is thankworthy, if a man for conscience toward God endure grief, suffering wrongfully.
20For what glory is it, if, when ye be buffeted for your faults, ye shall take it patiently? but if, when ye do well, and suffer for it, ye take it patiently, this is acceptable with God.
21For even hereunto were ye called: because Christ also suffered for us, leaving us an example, that ye should follow his steps:
Also of interest from 2Cor 12 is verse 10 which describes what the weaknesses are that were mentioned in verse 9. Paul had obviously received a very special revelation
1And Saul, yet breathing out threatenings and slaughter against the disciples of the Lord, went unto the high priest,
2And desired of him letters to Damascus to the synagogues, that if he found any of this way, whether they were men or women, he might bring them bound unto Jerusalem.
3And as he journeyed, he came near Damascus: and suddenly there shined round about him a light from heaven:
4And he fell to the earth, and heard a voice saying unto him, Saul, Saul, why persecutest thou me?
5And he said, Who art thou, Lord? And the Lord said, I am Jesus whom thou persecutest: it is hard for thee to kick against the pricks.
6And he trembling and astonished said, Lord, what wilt thou have me to do? And the Lord said unto him, Arise, and go into the city, and it shall be told thee what thou must do.
7And the men which journeyed with him stood speechless, hearing a voice, but seeing no man.
8And Saul arose from the earth; and when his eyes were opened, he saw no man: but they led him by the hand, and brought him into Damascus.
9And he was three days without sight, and neither did eat nor drink.
10And there was a certain disciple at Damascus, named Ananias; and to him said the Lord in a vision, Ananias. And he said, Behold, I am here, Lord.
11And the Lord said unto him, Arise, and go into the street which is called Straight, and enquire in the house of Judas for one called Saul, of Tarsus: for, behold, he prayeth,
12And hath seen in a vision a man named Ananias coming in, and putting his hand on him, that he might receive his sight.
13Then Ananias answered, Lord, I have heard by many of this man, how much evil he hath done to thy saints at Jerusalem:
14And here he hath authority from the chief priests to bind all that call on thy name.
15But the Lord said unto him, Go thy way: for he is a chosen vessel unto me, to bear my name before the Gentiles, and kings, and the children of Israel:
16For I will shew him how great things he must suffer
for my name’s sake.
17And Ananias went his way, and entered into the house; and putting his hands on him said, Brother Saul, the Lord, even Jesus, that appeared unto thee in the way as thou camest, hath sent me, that thou mightest receive thy sight, and be filled with the Holy Ghost.
18And immediately there fell from his eyes as it had been scales: and he received sight forthwith, and arose, and was baptized.
19And when he had received meat, he was strengthened. Then was Saul certain days with the disciples which were at Damascus.
20And straightway he preached Christ in the synagogues, that he is the Son of God.
21But all that heard him were amazed, and said; Is not this he that destroyed them which called on this name in Jerusalem, and came hither for that intent, that he might bring them bound unto the chief priests?
22But Saul increased the more in strength, and confounded the Jews which dwelt at Damascus, proving that this is very Christ.
13At midday, O king, I saw in the way a light from heaven, above the brightness of the sun, shining round about me and them which journeyed with me.
14And when we were all fallen to the earth, I heard a voice speaking unto me, and saying in the Hebrew tongue, Saul, Saul, why persecutest thou me? it is hard for thee to kick against the pricks.
15And I said, Who art thou, Lord? And he said, I am Jesus whom thou persecutest.
16But rise, and stand upon thy feet: for I have appeared unto thee for this purpose, to make thee a minister and a witness both of these things which thou hast seen, and of those things in the which I will appear unto thee;
17Delivering thee from the people, and from the Gentiles, unto whom now I send thee,
18To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me.
Without a doubt, anyone having such a massive revelation and repentance would be invited to speak at almost any protestant church alive today. To keep Paul from glorying in this incredible journey he was given something that would keep him from being different from other believers. Some weakness would be bestowed to him that all believers share for thier faith in Christ. Notice Acts 9 verse 16.
2 Timothy 3:11-12
11Persecutions, afflictions, which came unto me at Antioch, at Iconium, at Lystra; what persecutions I endured: but out of them all the Lord delivered me.
12Yea, and all that will live godly in Christ Jesus shall
Scripture is clear and plain when saying what Paul’s thorn