Summary: Paul was direct and focused on what he had to do; he was a messenger of Christ, not of himself or anyone else and he knew it.
16 For though I preach the gospel, I have nothing to glory of: for necessity is laid upon me; yea, woe is unto me, if I preach not the gospel!
17 For if I do this thing willingly, I have a reward: but if against my will, a dispensation of the gospel is committed unto me.
18 What is my reward then? Verily that, when I preach the gospel, I may make the gospel of Christ without charge, that I abuse not my power in the gospel.
The great English preacher Charles Spurgeon once said, “The gospel is preached in the ears of all men; it only comes with power to some. The power that is in the gospel does not lie in the eloquence of the preacher otherwise men would be converters of souls. Nor does it lie in the preacher’s learning; otherwise it could consist of the wisdom of men. We might preach till our tongues rotted, till we should exhaust our lungs and die, but never a soul would be converted unless there were mysterious power going with it – the Holy Ghost changing the will of man. O Sirs! We might as well preach to stone walls as preach to humanity unless the Holy Ghost be with the word, to give it power to convert the soul.”
Other than Jesus Christ, the greatest man of New Testament times was the apostle Paul. In fact, Paul was the greatest man in everything he did and if you go back to the time when his life was not lived in Christ, through Christ and for Christ, he was even great in what he did then. Someone said Paul was great in everything he did whether it was good or whether it was bad because he did nothing half way. If you consider him as a sinner, he was exceeding sinful — that's what he said, "exceeding sinful." He gave description of himself—he said, “For the good that I would I do not: but the evil that I would not, that I do.”
It depends upon how you view or consider Paul, if you consider him as a persecutor, he was mad against Christians — he persecuted them even in strange cities. He was not content to persecute them at home — he had to travel even to Damascus with letters giving him permission to destroy the people of Christ. He was so bold until he didn’t mind holding coats and watching as Stephen was stoned to death. If you consider the apostle as a convert, his conversion was remarkable; he met Christ in a real and personal way on the road to Damascus, blinded by the light, falling into the dust, looking up into that light, crying, "Lord what wilt Thou have me to do?"
If you consider this man as a preacher of the gospel, he stands out as the prince of preachers, the greatest of them all, crying, "I am ready to preach the gospel to them that are at Rome also; I am determined to know nothing among you, save Jesus Christ and him crucified." "God forbid," he said, "that I should glory save in the cross of my Lord and Saviour, Jesus Christ." Whatever Paul did, he did with all his heart; he did nothing halfway. If he was rebelling, he was rebelling; if he was bowing, he was bowing; if he was worshipping, he was worshipping; if he was preaching the gospel, he was preaching the gospel.