“How, then, can they call on the one they have not believed in? And how can they believe in the one of whom they have not heard? And how can they hear without someone preaching to them? And how can anyone preach unless they are sent? As it is written: ‘How beautiful are the feet of those who bring good news!'”
In the previous verse, Paul expressed that “everyone who calls on the name of the Lord will be saved.” And this expression is similar to verse 10, where he says that “It is with your mouth you profess your faith and are saved.” Then in these two verses, Paul describes what must happen before a person can call on the name of the Lord.
Calling on the name of the Lord is equivalent to discipleship, taking up your cross, and following Jesus. And that cannot be done without first believing.
In this passage, believing in Jesus is an intellectual exercise. It means that you accept that what you have heard about Jesus is true.
But how can one believe in Jesus without first hearing the truth? And how can they hear unless someone tells them?
In this, Paul expresses the importance of sharing the gospel with other people. If we do not tell others, they may never hear. And if they do not hear, they cannot believe and then call on the name of the Lord. So, how beautiful are the feet of those who share the gospel with others? Without them, none would be saved.