Albert Barnes Commentary 1 Thessalonians 1:8

"For from you hath sounded forth the word of the Lord, not only in Macedonia and Achaia, but in every place your faith to God-ward is gone forth; so that we need not to speak anything." — 1 Thessalonians 1:8 (ASV)

For from you sounded out the word of the Lord. The truths of religion were thus spread widely. The word translated 'sounded out,' exēchētai, refers to the sounding of a trumpet (Bloomfield), and the idea is that the gospel was proclaimed like the resonant voice of a trumpet echoing from place to place. (Revelation 1:10). Their influence had an effect in spreading the gospel in other places, as if the sound of a trumpet echoed and re-echoed among the hills and through the valleys of the classic land of Greece. This seems to have occurred in two ways:

1. Involuntarily; that is, the necessary result of their conversion, even without any direct purpose of their own, would produce this effect. Their central and advantageous commercial position, the fact that many of them were accustomed to visiting other places, and the fact that they were visited by people from other lands, would naturally contribute to this result.

2. However, this does not appear to be all that is intended. The apostle commends them in such a way as to make it certain that they were voluntary in spreading the gospel; that they made decided efforts to take advantage of their position to send the knowledge of the truth to other regions. If so, this is an interesting example of one of the first efforts made by a church to spread the gospel and send it to those who lacked it. It is quite probable that they sent out members of their church—messengers of salvation—to other parts of Macedonia and Greece, so that they might communicate the same gospel to others. (See Doddridge).

But also in every place. Thessalonica was connected in its commercial relations not only with Macedonia and mainland Greece but also with the ports of Asia Minor, and likely with even more distant regions. The meaning is that in all the places with which they traded, the effect of their faith was seen and talked about.

Faith to God-ward. This means fidelity toward God. They showed that they had a true belief in God and in the truth He had revealed.

So that we need not to speak anything. That is, wherever we go, we do not need to say anything about the fact that you have turned to the Lord, or about the character of your piety. These things are made sufficiently known by those who come from you, by those who visit you, and by your zeal in spreading the true religion.