The heartiness with which he speaks here justifies the inference that he had had experiences of an opposite and disappointing kind. Twice in Asia (Acts xvi. 6 f.) he had been forbidden by the Spirit to preach at all; he could not argue that the people so passed by were specially favoured of God. Often, especially in his intercourse with the Jews, he must have spoken, like Isaiah, with the depressing consciousness that it was all in vain; that the sole issue would be to blind their eyes and harden their hearts and seal them up in impenitence. In Corinth, just before writing this letter, he had come forward with unusual trepidation--in weakness and fear and much trembling; and though there also the Holy Spirit and a divine power brought home the gospel to men's hearts, he seems to have been so far from that inward assurance which he enjoyed at Thessalonica, that the Lord appeared to him in a vision by night to reveal the existence of an election of grace even in Corinth. "Fear not: I have much people in this city." In Thessalonica he had no such sinking of heart. He came thither, as he hoped to go to Rome, in the fulness of the blessing of Christ (Rom. xv. 29). He knew in himself that God had given it to him to be a true minister of His grace; he was full of power by the Spirit of the Lord. That is why he says so confidently, "Knowing your election."
The Apostle explains himself more precisely when he writes, "not in word only, but in power and in the Holy Ghost and in much assurance." The gospel must come in word at least; but what a profanation it is to preach it only in word. Not preachers only, but all Christians, have to be on their guard, lest familiarity rob the great words of the gospel of their reality, and they themselves sink into that worst atheism which is for ever handling holy things without feeling them. How easy is it to speak of God, Christ, redemption, atonement, sanctification, heaven, hell, and to be less impressed and less impressive than if we were speaking of the merest trivialities of every-day life. It is hard to believe that an apostle could have seen such a possibility even from afar; yet the contrast of "word" and "power" leaves no room to doubt that such is his meaning. Words alone are worthless. No matter how brilliant, how eloquent, how imposing they may be, they cannot do the work of an evangelist. The call to this requires "power."
No definition of power is given; we can only see that it is that which achieves spiritual results, and that the preacher is conscious of possessing it. It is not his own, certainly: it works through the very consciousness of his own want of power; "when I am weak, then am I strong." But it gives him hope and confidence in his work. Paul knew that it needed a stupendous force to make bad men good; the forces to be overcome were so enormous. All the sin of the world was arrayed against the gospel; all the dead weight of men's indifference, all their pride, all their shame, all their self-satisfaction, all their cherished wisdom. But he came to Thessalonica _strong_ in the Lord, confident that his message would subdue those who listened to it; and therefore, he argued, the Thessalonians were the objects of God's electing grace.
"Power" stands side by side with the "Holy Ghost." In a sense, the Holy Ghost is the source of all spiritual virtues, and therefore of the very power of which we have been speaking; but the words are probably used here with some narrower meaning. The predominant use of the name in the New Testament bids us think of that divine fervour which the spirit kindles in the soul--that ardour of the new life which Christ Himself speaks of as fire. Paul came to Thessalonica aglow with Christian passion. He took that as a good omen in his work, a sign that God meant well to the Thessalonians. By nature men do not care passionately for each other as he cared for those to whom he preached in that city. They are not on fire with love, seeking each other's good in spiritual things; consumed with fervent longing that the bad should cease from their badness, and come to enjoy the pardon, the purity, and the company of Christ. Even in the heart of apostles--for though they were apostles they were men--the fire may sometimes have burned low, and a mission have been, by comparison, languid and spiritless; but at least on this occasion the evangelists were all on fire; and it assured them that God had a people waiting for them in the unknown city.