Followers of Jesus in Rome had to be careful about how they shared the good news of Jesus because they could be arrested or killed. Paul reminds the followers of Jesus in Rome of the most important thing in Romans 1:16:

For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes.

Paul wasn't ashamed of the gospel because he knew that It wasn't just a story - it was and still is powerful. It had changed his heart and that changed everything. The good news is for everyone who believes in him, and is worth sharing with others.