We follow Paul's example as witnesses found in Romans 1:16. ESV
11 For I long to see you, that I may impart to you some spiritual gift to strengthen you—
12 that is, that we may be mutually encouraged by each other's faith, both yours and mine.
13 I do not want you to be unaware, brothers, that I have often intended to come to you in order that I may reap some harvest among you as well as among the rest of the Gentiles.
14 I am under obligation both to Greeks and to barbarians, both to the wise and to the foolish.
15 So I am eager to preach the gospel to you also who are in Rome.
16 For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek.
17 For in it the righteousness of God is revealed from faith for faith, as it is written, “The righteous shall live by faith.”
How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? (Rom. 10:14 esv)