The idea of being imprisoned under sin represents being controlled by sin. Possible meanings are 1) “the scripture caused everyone to be controlled by sin” or 2) “the scripture says that everyone is controlled by sin.” (See: [[rc://en/ta/man/jit/figs-metaphor]])
The word “promise” represents what God promised. Alternate translation: “what God promised to those who have faith in Christ” (See: [[rc://en/ta/man/jit/figs-metonymy]])