This can be stated in active form. Alternate translation: "the law held us captive and we were in prison" or "the law held us captive in prison" (See: [[rc://en/ta/man/translate/figs-activepassive]])
The way the law controlled us is spoken of as if the law were a prison guard holding us as captives. Alternate translation: "the law controlled us like a prison guard" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This can be stated in active form, and who this faith is in can be stated clearly. Alternate translation: "until God would reveal that he justifies those who have faith in Christ" or "until God would reveal that he justifies those who trust in Christ" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-explicit]])