12 So then, just as sin entered the world through one man and death through sin, and so death spread to all people because all sinned–
13 for before the law was given, sin was in the world, but there is no accounting for sin when there is no law. 14 Yet death reigned from Adam until Moses even over those who did not sin in the same way that Adam (who is a type of the coming one) transgressed.
15 But the gracious gift is not like the transgression. For if the many died through the transgression of the one man, how much more did the grace of God and the gift by the grace of the one man Jesus Christ multiply to the many! 16 And the gift is not like the one who sinned. For judgment, resulting from the one transgression, led to condemnation, but the gracious gift from the many failures led to justification. 17 For if, by the transgression of the one man, death reigned through the one, how much more will those who receive the abundance of grace and of the gift of righteousness reign in life through the one, Jesus Christ!
Consequently, just as condemnation for all people came through one transgression, so too through the one righteous act came righteousness leading to life for all people. 19 For just as through the disobedience of the one man many were made sinners, so also through the obedience of one man many will be made righteous. 20 Now the law came in so that the transgression may increase, but where sin increased, grace multiplied all the more, 21 so that just as sin reigned in death, so also grace will reign through righteousness to eternal life through Jesus Christ our Lord.
Adam is a figure of Christ in just this respect:
that as his one sin brought death to all,
even when there was no personal sin,
so Christ's one act of obedience
brings unfailing righteousness
to those who are in Him,
even when they have no personal righteousness.