But the free gift is not like the trespass. For if many died through one man's trespass, much more have the grace of God and the free gift by the grace of that one man Jesus Christ abounded for many -Romans 5:15
We know that sin and death came to all men through the one act of Adam. Jesus came in the fullness of the Father, of grace and truth (John 1:14). And God being just and displaying his righteousness, looked over previous sins, through the one righteous act of Jesus. Through Christ, the grace of God has abounded and the free gift by this grace has come to many. What is the free gift that comes through the grace of God?
Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ. Through him, we have also obtained access by faith into this grace in which we stand, and we rejoice in hope of the glory of God - Romans 5:1-2, ESV
Through Jesus, we have obtained faith and have access to grace. By faith, we have been justified, " and are justified by his grace as a gift, through the redemption that is in Christ Jesus," (Romans 3:24). There is a gift, possibly many, that comes in grace. "But the free gift following many trespasses brought justification. For if, because of one man's trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ" (Romans 5:16). The grace of God and the free gift by the grace through the one man Jesus Christ abounded for many. (Romans 5:15). The free gift brought justification, and the free gift comes through grace.
For if, because of one man's trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ -Romans 5:17 ESV
The free gift brought justification, and the free gift is received through the overbounding of grace (where sin abounded through Adam, grace overabounds through receiving, obtaining faith through Jesus,) and a free gift we receive is righteousness in which we reign in life through Jesus. If we reign in life through the free gift of righteousness then the free gift can be said to be life. But without righteousness life is not obtainable. This righteousness is not our own, if we worked for it, it would be like a wage earned, therefore, it is by grace, The one righteous act of Jesus led to justification and life (Romans 5:18).
This scripture is a segue for what is to come in the next chapter, "therefore, what shall we say then? Are we to continue in sin that grace may abound?" ( Romans 6:1)