Paul here uses a figure of speech called hyperbole, a deliberate exaggeration, and not meant to be taken literally but intended to communicate something of the author’s emotional response to the greatness of what is described. In other words, although Paul is not asserting that the report about the Thessalonians’ faith has reached every square centimetre of the planet, he is expressing amazement at how far the news has travelled—farther than just Macedonia and Achaia.
8 For not only has the word of the Lord sounded forth from you in Macedonia and Achaia, but your faith in God has gone forth everywhere, so that we need not say anything.