In 2 Corinthians 12:7, Paul says, "Therefore, to keep me from being too elated, a thorn was given me in the flesh, a messenger of Satan to torment me, to keep me from being too elated."
Paul says that he asked God to take this thorn away from him, but that God responded with, "My grace is sufficient for you, for My strength is made perfect in weakness." (2 Corinthians 12:9)
There is no way to know for sure what Paul's thorn in the flesh was; however, we can look at the evidence in scripture to explore likely possibilities.
While there are some who claim they know what Paul's thorn in the flesh is, the truth is there is no way to know with absolute certainty. All we can do is understand the possibilities based on the evidence.
The likeliest possibilities, as will be seen by the scriptural evidence, are: illness, persecution, and sufferings.
In the context of 2 Corinthians 12, this thorn in the flesh was given to Paul 14 years ago after he had received a revelation, "...but I will go on to visions and revelations of the Lord. I know a person in Christ who fourteen years ago was caught up to the third heaven..." (2 Corinthians 12:2).
Paul has been boasting
about who he is, what he has done, and what he has experienced as a
sarcastic reply to the boast of the super-apostles. These super-apostles are false teachers according to Paul, which he speaks of in 2
Corinthians 11-12. (Even just calling these false teachers "super-apostles" is sarcasm.)
In the context of this section on Paul's vision, it appears that Paul is speaking of what happened to himself, but he is unable to plainly state it, as seen by his unwillingness to boast in the first place (see 2 Corinthians 11:30, 2 Corinthians 12:6-7, and 2 Corinthians 12:11).
If Paul is not speaking of himself being taken into heaven, then it does not make sense why he would speak of an unnamed individual when he is presenting his boast about his experiences and his vision, starting in 2 Corinthians 11.
Even if Paul is not speaking of himself, and this event did not happen to him fourteen years ago, there is no indication that Paul's vision or corresponding thorn in the flesh were recent events.
When Paul wrote this letter to the believers in Corinth, he likely no longer had this thorn in the flesh.
Instead, Paul is making the point that when he received this vision (whether about himself or someone else), he received a thorn in the flesh in order to keep him humble and weak so he would rely on God's strength.
"[God] said to me, 'My grace is sufficient for you, for power is made perfect in weakness.' So, I will boast all the more gladly of my weaknesses, so that the power of Christ may dwell in me. Therefore I am content with weaknesses, insults, hardships, persecutions, and calamities for the sake of Christ; for whenever I am weak, then I am strong." (2 Corinthians 12:9-10)
For more information on why the context indicates that Paul is speaking about himself when referring to this vision, see the Summary of 2 Corinthians.
One possibility is that Paul's thorn in the flesh is an illness. In particular, verses like Galatians 4:13 and Galatians 4:15 are often cited to indicate that Paul may have suffered from a long term illness, or even just to indicate that Paul did sometimes experience illness that God did not heal.
"You know that it was because of a physical infirmity that I first announced the gospel to you..." (Galatians 4:13) Some indicate that Paul may be referring to an illness here.
"What has become of the goodwill you felt? For I testify that, had it been possible, you would have torn out your eyes and given them to me." (Galatians 4:15)
The fact that Paul mentions this statement about eyes is thought by some to indicate that Paul had an illness affecting his eyesight.
The end of Galatians is often used to support this idea that Paul had issues with his eyesight, because Paul says, "See what large letters I make when I am writing in my own hand!" (Galatians 6:11) Paul often had someone else transcribe his letters (Romans 16:22), even though Paul is the actual author.
However, when Paul writes that he "announced the gospel" to them "because of a physical infirmity," it is possible he is referring to abuse suffered from persecution, as recorded in Acts 14:19-21 when Paul is stoned in Galatia.
"Then they stoned Paul and dragged him out of the city, supposing that he was dead. But when the disciples surrounded him, he got up and went into the city. The next day he went on with Barnabas to Derbe. After they had proclaimed the good news to that city and had made many disciples, they returned to Lystra, then on to Iconium and Antioch." (Acts 14:19-21)
Derbe and Lystra were both cities in Galatia.
With this information in mind, it can be seen that Paul's "physical infirmity" and issues with his eyes is likely due to having been stoned almost to death.
Another possibility is that Paul's Thorn in the Flesh is some form of persecution. This is a more likely view based on the context of 2 Corinthians 11-12.
Just before this section about the thorn in the flesh, Paul speaks of himself when he says in 2 Corinthians 11:23-30,
"...with far greater labors, far more imprisonments, with countless floggings, and often near death. Five times I have received from the Jews the forty lashes minus one. Three times I was beaten with rods. Once I received a stoning. Three times I was shipwrecked; for a night and a day I was adrift at sea...in toil and hardship, through many a sleepless night, hungry and thirsty, often without food, cold and naked. And, besides other things, I am under daily pressure because of my anxiety for all the churches. Who is weak, and I am not weak? Who is made to stumble, and I am not indignant? If I must boast, I will boast of the things that show my weakness."
Also, in the Old Testament, the phrase 'thorn in the flesh' is sometimes used to refer to people, such as in Numbers 33:55 "But if you do not drive out the inhabitants of the land from before you, then those whom you let remain shall be as barbs in your eyes and thorns in your sides; they shall trouble you in the land where you are settling."
We know that persecution is something that God would allow Paul to experience, as Paul mentions to Timothy, "Indeed, all who want to live a godly life in Christ Jesus will be persecuted." (2 Timothy 3:12)
However, there is a key verse in 2 Corinthians 11:30 where Paul states, "Who is weak...If I must boast, I will boast of the things that show my weakness." Paul makes a similar statement in 2 Corinthians 12:9, as well as in Philippians 4:13 when he is speaking of suffering by being hungry or being in need.
In 2 Corinthians 11:30, Paul says, "Who is weak...If I must boast, I will boast of the things that show my weakness."
Then Paul mentions his vision and the corresponding thorn in his flesh, and he says that God's response is, "'My grace is sufficient for you, for power is made perfect in weakness.' [To which Paul says] So, I will boast all the more gladly of my weaknesses, so that the power of Christ may dwell in me." (2 Corinthians 12:9)
In the context of 2 Corinthians, Paul refers to his sufferings as "his weakness" meaning that his current body is weak and vulnerable. This fact is a major part of Paul's discussion on being resurrected with an imperishable body in 2 Corinthians 4-6.
Also, continuing on to 2 Corinthians 12:10, Paul says, "Therefore I am content with weaknesses, insults, hardships, persecutions, and calamities for the sake of Christ; for whenever I am weak, then I am strong." (2 Corinthians 12:9-10)
Paul makes a similar statement, about relying of Christ's strength, in Philippians 4:13 when he says, "I can do all things through him who strengthens me."
In context, Paul is saying that this is the secret to being content when "being well-fed and of going hungry, of having plenty and of being in need." (Philippians 4:12)
Based on this evidence, it may be that Paul's thorn in the flesh is actually just some form of suffering related to being hungry, naked, or in need in some other way. After all, when Paul mentions boasting about his weaknesses in 2 Corinthians 11:30, he has just said, "in toil and hardship, through many a sleepless night, hungry and thirsty, often without food, cold and naked. And, besides other things, I am under daily pressure because of my anxiety for all the churches." (2 Corinthians 11:27-28)
Paul then makes these statements in 2
Corinthians 11-12 about boasting in his weakness and relying on
Christ's strength, which mirrors what he says in Philippians 4:12-13, as well as his explanation in 2 Corinthians 4-6 on our hope of being resurrected with an imperishable body.
Whatever Paul's thorn in the flesh may have been, Paul does state the purpose of it remaining in 2 Corinthians 12:7, "...to keep me from being too elated," meaning that it was for the sake of remaining humble and of being in need of God's strength after having received his vision.
Paul makes a similar statement at the beginning of his letter in 2 Corinthians 1:9 saying, "Indeed, we felt that we had received the sentence of death so that we would rely not on ourselves but on God who raises the dead."
A major theme in 2 Corinthians is the idea of relying on God's strength instead of our own, and the idea of God humbling us with our weaknesses (by being hungry, or becoming injured, etc.) to remind us that we are "clay jars" (2 Corinthians 4:7) and need God's strength.
In the end, the evidence for supporting that Paul had an illness is essentially nonexistent, since the verses in Galatians can be explained by the stoning Paul experienced as recorded in Acts 14:19-21.
Persecution may be a likely option based on the context of 2 Corinthians 11-12, as well as the Old Testament sometimes making references to people as thorns in the flesh.
However, physical suffering from lack of some basic need is an even more likely option due to the entire context of 2 Corinthians, with support from Philippians 4:12-13.
After all, if we were to receive a vision, wouldn't being cold or hungry remind us quickly that we are in weak and fragile bodies, and we need God's strength?
Either way, the point that Paul makes about the thorn in the flesh is that his response is: "So, I will boast all the more gladly of my weaknesses, so that the power of Christ may dwell in me." (2 Corinthians 12:9)