What does Romans 10:15 mean?

Beginning with his statement in verse 13, that all who call on the name of Jesus will be saved, Paul has been asking a series of leading questions. How will anyone call on Jesus—express saving faith in Him—unless they first believe in Him? And how will they believe in Him if they never hear about Him? And how will they hear about Him if nobody preaches the gospel to them?

Now Paul continues with the next logical question: How will anyone preach the gospel of Jesus unless they are sent by someone to do so? Paul's question shows that preaching is not the first step in the chain that leads to faith in Christ and calling on His name. Instead, sending is that first step.

Who does the sending? In the case of Paul and the other apostles who had been preaching the gospel around the world, it was Christ Himself who had sent them out. They had been commissioned by Jesus to preach the good news to the world (Matthew 28:18–20; Acts 9:15).

Paul next quotes from Isaiah 52:7 to make the case that this sending of the preachers with this specific good news about Jesus was prophesied long ago: "How beautiful are the feet of those who preach the good news!"