Romans 1:15 "So, for my part, I am eager to preach the gospel to you also who are in Rome."

The gospel is only for unbelievers right?  Wrong!

Romans 1:8 "First, I thank my God through Jesus Christ for you all, because your faith is being proclaimed throughout the whole world."

How often is the gospel conveyed (or implied) solely as a means of evangelism or mission work?  Paul here confirms what orthodox Christianity has always confirmed, the gospel needs to be preached to all, believers or not.  There is so much depth to the gospel message (as we read in Romans) that we can spend a lifetime exploring it and growing in knowledge and love for Christ.

Everyone needs the gospel.  And it is all believers responsibility to proclaim it.

1 Corinthians 2:2 "For I determined to know nothing among you except Jesus Christ, and Him crucified."