In Galatians 1-2 one of the dominant themes is the fear of man. Paul, in lovingly yet boldly confronting the Galatians, and exposing the false teachers was living in the fear of God rather than the fear of man. He was not accomodating the gospel to please anyone, recognizing the divine origin of that gospel.
On the other hand you have the account of Peter in Antioch. He, again, succombs to the fear of man (his besetting sin, and lest you’re too hard on him- you’ve got some too!). He shrunk back from fellowship with Gentile Christians and hypocritically followed the dietary laws out of fear, not conviction. And Barnabas joined him. Two important Christian leaders fell victim to this sin- and Paul displayed gospel boldness by confronting Peter publicly.
While not referring to these events, Milton Vincent talks about gospel boldness in A Gospel Primer for Christians.
“Boldness is critical. Without boldness, my life story will be one of great deeds left undone, victories left unwon, petitions left unprayed, and timely words unsaid. If I wish to live only a pathetically small portion of the life God has prepared for me, then I need no boldness. But if I want my life to bloom full and loom large for the glory of God, then I must have boldness- and nothing so nourishes boldness in me like the gospel!