What does Romans 10:17 mean?

This famous verse builds on Paul's quote of Isaiah in the previous verse. There Isaiah asks the Lord "who has believed what he has heard from us?" (Isaiah 53:1). Paul was showing that a refusal to believe what God says amounts to disobedience. That, according to Scripture, is the root problem when people hear the gospel and do not accept it (John 5:39–40; 7:17). Those who disbelieve do so because, on some level, they do not want to believe.

Now, though, Paul writes that when believing happens, it is through hearing what the Lord says "through the word of Christ." Paul seems to be referring to his prior chain of steps which must occur to bring a person to the point of calling on the Lord. Christ sends out His representatives to preach the gospel. Those who hear it have the opportunity to believe. Those who believe call on Christ. And all who call on the name of Christ will be saved (Romans 10:13).