The Prisoner of Christ Jesus

In the book of Acts, Paul calls himself a prisoner of king Jesus. He's sitting in a Roman prison cell, but he's like, yeah, the Roman's incidental,. And for whose sake is he sitting in that prison cell? What's he saying? You guys, you, Gentiles. Now he's not laying a guilt trip right now. He's actually just alluding to a story that you're supposed to know.