Albert Barnes Commentary 1 Thessalonians 1:5

"how that our gospel came not unto you in word only, but also in power, and in the Holy Spirit, and [in] much assurance; even as ye know what manner of men we showed ourselves toward you for your sake." — 1 Thessalonians 1:5 (ASV)

For our gospel came not unto you. This was when it was first preached (Acts 17:1–3). Paul speaks of it as "our gospel" because it was the gospel preached by him, Silas, and Timothy. Compare 2 Thessalonians 2:14 and 2 Timothy 2:8. He did not mean to say that the gospel had been originated by him, but only that he had delivered the good news of salvation to them. He is here stating the evidence that had been given that they were a church "chosen by God." He refers, first, to the manner in which the gospel was received by them (1 Thessalonians 1:5–7); and, secondly, to the spirit which they themselves manifested in sending it abroad (1 Thessalonians 1:8–10).

In word only. It was not merely spoken, or merely heard. It produced a powerful effect on the heart and life. It was not a mere empty sound that produced no other effect than to entertain or amuse. Compare Ezekiel 33:32.

But also in power. That is, in such power as to convert the soul. The apostle evidently does not refer to any miracles that were performed there, but to the effect of the gospel on those who heard it. It is possible that miracles were performed there, as they were in other places; but there is no mention of such a fact, and it is not necessary to suppose this to understand the full meaning of this language.

There was great power manifested in the gospel in its leading them to break off from their sins, to abandon their idols, and to give their hearts to God. This is more fully explained in the comments on 1 Corinthians 2:4.

And in the Holy Ghost. Compare the comments on 1 Corinthians 2:4.

It is there called the demonstration of the Spirit.

And in much assurance. That is, with firm conviction, or full persuasion of its truth. It was not embraced as a doubtful thing, and it did not produce the effect on the mind which is caused by anything that is uncertain in its character. Many seem to embrace the gospel as if they only half believed it, or as if it were a matter of very doubtful truth and importance; but this was not the case with the Thessalonians.

There was the firmest conviction of its truth, and they embraced it "heart and soul" (Colossians 2:2; Hebrews 6:11). From all that is said in this verse, it is evident that the power of God was remarkably manifested in the conversion of the Thessalonians, and that they embraced the gospel with an uncommonly strong conviction of its truth and value.

This fact will account for the subsequent zeal which the apostle so much commends in them—for it is usually true that the character of piety in a church, as it is in an individual, is determined by the views with which the gospel is first embraced, and the purposes which are formed at the beginning of the Christian life.

As ye know what manner of men, etc. Paul often appeals to those among whom he had labored as competent witnesses regarding his own conduct and character. See 1 Thessalonians 2:9–10; Acts 20:33–35.

He means here that he and his fellow laborers had set them an example, or had shown what Christianity was by their way of living, and that the Thessalonians had become convinced that the religion they taught was real. The holy life of a preacher goes far to confirm the truth of the religion he preaches and is among the most effective means of inducing them to embrace the gospel.