Romans 5:18-19 meaning

Paul writes, So then as through one transgression there resulted condemnation to all men, even so through one act of righteousness there resulted justification of life to all men (v 18).

The one transgression that Paul is referring to is the sin of Adam when he ate the fruit in the Garden of Eden (Genesis 3:6). God gave Adam one law, He forbade that he eat from the tree of the knowledge of good and evil (Genesis 2:17). Then God left it to Adam to choose what to do. In doing this, God set up a governing structure of self-governance, with two pillars:

• Rule of law (in this case, only one law)
• Consent of the governed (Adam got to choose whether to obey God or follow his own way)

God let Adam choose, but God set the consequence, telling Adam that if he chose to eat of the forbidden tree, he would experience death.

God keeps His promises, and just as He said, when Adam sinned, there resulted condemnation to all men (Genesis 2:17). From Adam's choice, sin entered the world and spread to every single person thereafter. Thus, this one transgression then resulted in bringing condemnation of death to all men.

But just as death entered the world through the one transgression that was Adam's sin, Jesus's death on the cross is one act that allows all people to gain justification of life. Jesus's death of the cross was one act of righteousness since Jesus knew no sin (2 Corinthians 5:21). This one sacrifice paid for all sins, for all time (Hebrews 9:12).

The justification of life is what results for each person who believes on Jesus (John 3:14-15). The word translated life is "zoe" which refers to the quality of life, the degree to which we are fulfilled. The word translated justification is the Greek word "dikaiosis" which carries the idea of being set free, being declared innocent. Because of Jesus's death and resurrection, those who believe are set free from sin, and now have the power to live in harmony with God's design (righteousness). Living in God's (good) design leads to our greatest fulfillment of life (Romans 6:22; Galatians 5:13).

The term justification of life echoes verse 15 where Paul says that the free gift of grace covers every single sin of anyone who believes.

Paul continues the contrast between Adam's sin and Jesus's perfect life: By the one man's [Adam's] disobedience the many were made sinners (v 19). Through Adam's sin, each human born of a human father inherited that sin, and therefore inherited death. Jesus did not inherit that sin, being born of a virgin; He had God as His Father.

Unlike Adam's sin, Jesus's sacrifice is a gift that we can accept or reject. By Christ's obedience, we are reconciled with God and given the power to live righteously through faith: Through the obedience of the One [Jesus] the many will be made righteous (v 19). 

Anyone who believes is made righteous in God's sight simply because they believed (John 3:14-15; Romans 4:1-3). Thereafter, the experience of righteousness comes through living by faith, faith that God's ways are for our best. Christ has opened up the door to living the life God wants us to live, the newness of life.

We can be restored to God's creative design through walking by faith daily. This entails obeying God's will for our lives, which is to be set apart/sanctified from the exploitative ways of the world (1 Thessalonians 4:3). In order to gain the greatest reward available from living life on this earth, we should walk in the resurrection power of Jesus and live apart from the world to such a degree that we suffer the sufferings Christ (Romans 8:17b; Philippians 2:8; Revelation 3:21). This is all made possible by the obedience of one man, Jesus Christ.