Definition and Overview:
Righteousness through faith in Jesus Christ is a foundational doctrine in Christian theology, emphasizing that individuals are justified and made righteous before God not by their own works or merits, but through faith in Jesus Christ. This concept is central to the teachings of the New Testament and is particularly expounded in the writings of the Apostle Paul.

Biblical Foundation:
The doctrine of righteousness through faith is primarily derived from the Pauline epistles. In Romans 3:22, Paul writes, "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 place their faith in Christ, regardless of their background or previous adherence to the Law.

The Role of the Law:
The Law, given through Moses, served as a guide and a means to reveal sin, but it was never intended as a means to achieve righteousness. Romans 3:20 states, "Therefore no one will be justified in His sight by works of the law. For the law merely brings awareness of sin" . The Law highlights humanity's inability to attain righteousness on their own, pointing instead to the need for a Savior.

Faith and Justification:
Justification is a legal term signifying a declaration of righteousness. In Romans 5:1, Paul declares, "Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ" . This peace with God is a result of being justified, or declared righteous, through faith in Jesus Christ, not through human effort.

The Example of Abraham:
Abraham is often cited as the exemplar of righteousness through faith. Romans 4:3 states, "Abraham believed God, and it was credited to him as righteousness" . Abraham's faith, rather than his works, was the basis for his righteousness, serving as a prototype for all believers.

The Role of Grace:
Grace is the unmerited favor of God, and it is through grace that righteousness is imparted to believers. Ephesians 2:8-9 emphasizes, "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 salvation and righteousness are gifts from God, received through faith.

The Transformative Power of Faith:
Faith in Jesus Christ not only justifies but also transforms the believer. In Galatians 2:20, Paul writes, "I have been crucified with Christ, and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave Himself up for me" . This transformation is evidence of the new life that comes through faith, characterized by a growing conformity to the image of Christ.

Implications for Christian Living:
Righteousness through faith calls believers to live in a manner worthy of their calling. Philippians 3:9 expresses the desire to "be found in Him, not having my own righteousness from the law, but that which is through faith in Christ, the righteousness from God on the basis of faith" . This pursuit of righteousness is not about earning God's favor but living out the reality of the righteousness already received through faith.

Conclusion:
The doctrine of righteousness through faith in Jesus Christ is a cornerstone of Christian belief, affirming that salvation and right standing with God are gifts received through faith, not earned by human effort. This truth liberates believers from the burden of the Law and empowers them to live transformed lives in Christ.