Jesus was the second Adam as, like the first Adam He entered the world free from sin. Jesus was the New Adam as, unlike the first He did not let temptation lead Him into sin, but remained sinless throughout His life.
Adam sinned against God and all his descendants are tainted by that disobedience and yet can find justification, not through any act of their own, but by the selfless obedience of Jesus who allows us to be justified by faith in Him.
It is interesting to consider what Paul could have meant by “justification.” Paul was familiar with Jewish law and court system. Unlike courts today there was no prosecutor or defence lawyer. The accuser and defendant both gave their statements to a judge who would then decide who was right and that person would be justified. If the defendant was justified it was like an acquittal in modern law.
Paul writes to the Galatians (2:16) “yet we know that a person is justified not by the works of the law but through faith in Jesus Christ. And we have come to believe in Christ Jesus, so that we might be justified by faith in Christ.”
It is good to know that we are not justified by some legal loophole that lets a guilty person go free but we are truly justified and correctly free to worship God without our past sinful nature coming between us and God. We are not simply changed we are renewed; 2 Corinthians 5:17 “So if anyone is in Christ, there is a new creation: everything old has passed away; see, everything has become new!”
We may sometimes feel worthless or helpless but we should always remember that we have been changed by Jesus, not by any act that we have done but by His selfless sacrifice on the cross. We are not merely forgiven but we are transformed into something different by our acceptance of Him and His death.