Definition and Overview:
Righteousness through Christ refers to the Christian doctrine that believers are made righteous before God not by their own works or merits, but through faith in Jesus Christ. This righteousness is imputed to believers as a result of Christ's sacrificial death and resurrection, fulfilling the requirements of the Law and reconciling humanity to God.

Biblical Foundation:
The concept of righteousness through Christ is deeply rooted in the New Testament, particularly in the writings of the Apostle Paul. In Romans 3:22, Paul states, "And this righteousness from God comes through faith in Jesus Christ to all who believe. There is no distinction." This verse underscores the universality of this righteousness, available to all who have faith in Christ, regardless of their background or previous adherence to the Law.

The Role of Faith:
Faith is central to receiving righteousness through Christ. In Ephesians 2:8-9, Paul writes, "For it is by grace you have been saved through faith, and this not from yourselves; it is the gift of God, not by works, so that no one can boast." This passage highlights that righteousness is a gift from God, not something that can be earned through human effort. Faith in Christ is the means by which believers receive this gift.

Imputation of Righteousness:
The doctrine of imputation is crucial to understanding righteousness through Christ. In 2 Corinthians 5:21, Paul explains, "God made Him who knew no sin to be sin on our behalf, so that in Him we might become the righteousness of God." Here, the sinless Christ takes on the sins of humanity, and in exchange, believers are credited with His righteousness. This divine exchange is the foundation of the believer's right standing before God.

Justification by Faith:
Justification is a legal term used in the New Testament to describe the act of God declaring a sinner righteous on the basis of faith in Christ. Romans 5:1 states, "Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ." Justification is not a process but a one-time act of God, resulting in a new status for the believer.

Transformation and Sanctification:
While righteousness through Christ is a positional truth, it also leads to practical transformation in the believer's life. Philippians 1:11 speaks of being "filled with the fruit of righteousness that comes through Jesus Christ, to the glory and praise of God." This indicates that the imputed righteousness of Christ results in a life that increasingly reflects His character and holiness.

Old Testament Foreshadowing:
The concept of righteousness through faith is not exclusive to the New Testament. The Old Testament provides foreshadowing of this doctrine, particularly in the life of Abraham. Genesis 15:6 states, "Abram believed the LORD, and it was credited to him as righteousness." Paul references this in Romans 4:3 to illustrate that righteousness by faith has always been God's plan.

Christ as the Fulfillment of the Law:
Christ's role in fulfilling the Law is essential to understanding righteousness through Him. In Matthew 5:17, Jesus declares, "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them, but to fulfill them." By perfectly fulfilling the Law, Christ provides a way for believers to be righteous apart from the Law's demands.

Conclusion:
Righteousness through Christ is a foundational doctrine of the Christian faith, emphasizing that salvation and right standing with God are gifts of grace received through faith in Jesus Christ. This righteousness is both a legal declaration and a transformative reality, leading believers to live lives that reflect the character of Christ.