wondering,
While the language of imputation is not used explicitly in Romans 5, the concept or reality is certainly present (cf. Psalm 32:2; Romans 4:8; 5:13 and 2 Cor 5:19). Imputation introduces the idea that sinners are constituted guilty independent of and prior to their own personal sin.
In Rom 5:12-20, we have the historical view of the imputation of sin.
Note Rom 5:12 (NASB), 'Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned'.
- In vv. 15-19 we have the one trespass of the one man and that is parallel to the language of v. 12, 'all sinned', i.e. through the one man's sin, all people sinned or became sinners. Sin was imputed to every human being.
- Verses 13–14 form a parenthesis in the argument.
- The 'just as' / 'and so' in Rom 5:12a and 5:12b begin an unfinished sentence whose syntax is not completed until 5:19a and 19b, 'For as through the one man’s disobedience the many were made sinners, even so through the obedience of the One the many will be made righteous' (NASB). The syntax of 'just as' / 'even so' in 5:19a and 19b connect with 5:12.
Thus by one man's act of disobedience is imputed to the entire human race sin and death.
This is compared to another act of obedience that results in life and righteousness. This is the Adam vs Christ analogy of imputation. Adam imputes disobedience. Christ imputes obedience. See Rom 5:15-18.
Oz