2Corinthians 12:6-9 For 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 seen me to be, or that he heard of me. 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. 

‘For 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.’ Even if Paul desired to glory he would not be senseless (11:16), for God knows that what he says was the truth. He will stop lest any man thinks that he is more than what he is and can demonstrate.

‘Exalted’ [Greek: huperairomai] Used only here and of the Antichrist exalting himself above all that is called God (2Thess. 2:4). This is what caused Lucifer to fall (Isa. 14:12-14; Ezek. 28:11-17; 1Tim. 3:6). God did not want Paul to exalt himself through the abundance of revelations given him, so He permitted him to have the thorn in the flesh to keep him humble.

‘Messenger’ [Greek: angelos] translated “angel” 179 times and “messenger” 7 times. It is never translated as “disease” or “physical infirmity” and never means any such thing. The simple explanation of the thorn in the flesh is that an angel of satan, a messenger of satan with the name of Alexander did Paul much evil (1Tim. 1:19-20) and who became an enemy of the gospel (2Tim. 4:14-15; Acts 19:33).

‘Buffet’ [Greek: kolaphizo] to cuff; to box on the ear (Matt. 26:67; Mark 14:65; 1Cor. 4:11; 1Pet. 2:20).

‘My grace is sufficient for thee: for my strength is made perfect in weakness.’ God assured Paul that grace would be provided for him to suffer all things; and that he should learn to depend wholly upon the power of God (12:8-9).

‘Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me.’ Paul learned to glory in his infirmities so that the power of Christ could rest upon him (12:9-10; Acts 9:16).