Was that thorn in Paul's flesh sin?
First, here is the verse that many people who believe in greasy grace point to in trying to justify their own sin by claiming that Paul also struggled with sin. The mindset they have is, "if Paul sinned then I'm OK in my own sin". 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. 2 Corinthians 12:7 Now verses 7 through 10 in order to capture the full and correct context: 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. 2 Corinthians 12:7-10 God let Paul know that God's grace was sufficient and essentially said this thorn would remain. Now it makes absolutely no sense to say that the thorn in Paul's flesh was sin knowing that Jesus literally died and spilt His blood so that all men could be saved from sin. Jesus died so that we could be freed from sin, not to remain in the bondage of sin. Paul said the thorn was an infirmity which he included along side of reproaches, necessities, persecutions, and distresses that he endured for Christ's sake. None of these were sins but instead they were trials of life that he was empowered by God to endure for God's glory. Long before Paul came along someone else was given a thorn in his flesh. It was actually an extremely severe thorn, if you will, and this man endured it without sinning by not cursing God as his wife told him to. This attack by Satan on Job's flesh was not sin on Job's part just as it wasn't sin with Paul. And the Lord said unto Satan, Hast thou considered my servant Job, that there is none like him in the earth, a perfect and an upright man, one that feareth God, and escheweth evil? and still he holdeth fast his integrity, although thou movedst me against him, to destroy him without cause.  And Satan answered the Lord, and said, Skin for skin, yea, all that a man hath will he give for his life.  But put forth thine hand now, and touch his bone and his flesh, and he will curse thee to thy face.  And the Lord said unto Satan, Behold, he is in thine hand; but save his life.  So went Satan forth from the presence of the Lord, and smote Job with sore boils from the sole of his foot unto his crown.  And he took him a potsherd to scrape himself withal; and he sat down among the ashes.  Then said his wife unto him, Dost thou still retain thine integrity? curse God, and die.  But he said unto her, Thou speakest as one of the foolish women speaketh. What? shall we receive good at the hand of God, and shall we not receive evil? In all this did not Job sin with his lips. Job 2:3-10 If Paul was struggling with sin then he absolutely would not have encouraged others to do as he was doing. That also makes no sense at all. Wherefore I beseech you, be ye followers of me. 1 Corinthians 4:16 Be ye followers of me, even as I also am of Christ. 1 Corinthians 11:1 Brethren, be followers together of me, and mark them which walk so as ye have us for an ensample. Philippians 3:17 Paul encouraged others to not sin. He would have been a hypocrite if he was willingly and knowingly living in sin himself while telling others to not sin. Awake to righteousness, and sin not; for some have not the knowledge of God: I speak this to your shame. 1 Corinthians 15:34 What shall we say then? Shall we continue in sin, that grace may abound?  God forbid. How shall we, that are dead to sin, live any longer therein? Romans 6:1-2 What then? shall we sin, because we are not under the law, but under grace? God forbid.  Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; whether of sin unto death, or of obedience unto righteousness?  But God be thanked, that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine which was delivered you.  Being then made free from sin, ye became the servants of righteousness. Romans 6:15-18 So, the answer is no. The thorn in Paul's flesh was not sin.