From the Conclusion of John Fesko’s book, Justification:

Dr. Fesko drives the nail home in Justification: Understanding the Classic Reformed Doctrine by John Fesko:

If Christ is the last Adam, and he is the fountainhead of the age to come, of the eschaton, then the justification pronounced over those who place their faith in him is eschatological, final, and irreversible. This means that the verdict from the final judgment on the last day has been declared in the present. Justification does not merely restore the sinner to the potentially defectible state of the first Adam only to face probation once again. Or, in simpler terms, justification does not merely return us to the garden. Rather, noting the inherently eschatological nature of justification tells us that Christ has performed the work for us and that we enter the eternal state by faith alone in him; by faith, we are propelled into the indefectible state of the last Adam. (p. 409)

Lastly, it is the nature of Adam's probation in the garden that causes many to see the importance of the law-gospel hermeneutic in Scripture. The law is not, contrary to popular opinion, an evangelical aid given to man after his sins are forgiven to assist him in his journey of moral transformation that culminates in his declaration righteousness at the final judgment. Rather, the law represents the requirement of perfect obedience, the requirement that God demanded of Adam, and later of Israel at Sinai. It was the requirement that all failed to meet, save the last Adam. Therefore, the law brings those same demands that God placed upon Adam, his disobedient son, in the garden-temple; upon Israel his stiff-necked firstborn son at the foot of Sinai; and upon Jesus, the Son of man, God’s only begotten Son in whom he was well pleased, who was born under the law to redeem us from its curse. The demands of the law therefore drive sinners to look outside of themselves to the perfect obedience of another, to the righteousness of Jesus Christ. Our faith is extraspective, not introspective. It is the covenant of works that enables us to see that if Adam could not be justified by his works though he was sinless and righteous, we cannot be justified by our works in any sense. Only the perfect obedience of the last Adam justifies us. (p. 411)

[emphasis added]