Definition and Overview:
Salvation by grace through faith is a foundational doctrine in Christian theology, emphasizing that human beings are saved from sin and its consequences not by their own efforts or merits, but by the unmerited favor of God, received through faith in Jesus Christ. This doctrine underscores the belief that salvation is a gift from God, accessible to all who believe, and not a result of human works.

Biblical Foundation:
The concept of salvation by grace through faith is primarily derived from the New Testament, particularly the writings of the Apostle Paul. Ephesians 2:8-9 states, "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 the gratuitous nature of salvation and the exclusion of human boasting, as salvation is not earned but given.

Grace:
Grace, in the biblical context, refers to the unmerited favor and love of God towards humanity. It is through grace that God initiates the process of salvation. Romans 3:23-24 explains, "for all have sinned and fall short of the glory of God, and are justified freely by His grace through the redemption that is in Christ Jesus." Here, grace is depicted as the means by which God justifies sinners, offering redemption through Jesus Christ.

Faith:
Faith is the means by which individuals receive the grace of God. It involves trust and belief in the person and work of Jesus Christ. Hebrews 11:1 describes faith as "the assurance of what we hope for and the certainty of what we do not see." Faith is not merely intellectual assent but involves a personal trust in Jesus Christ as Lord and Savior.

Role of Jesus Christ:
Central to the doctrine of salvation by grace through faith is the role of Jesus Christ. His sacrificial death and resurrection are the basis for salvation. Romans 5:8-9 states, "But God proves His love for us in this: While we were still sinners, Christ died for us. Therefore, since we have now been justified by His blood, how much more shall we be saved from wrath through Him!" Jesus' atoning sacrifice is the means by which grace is extended to humanity.

Justification and Sanctification:
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 Jesus Christ. Romans 5:1 affirms, "Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ." Sanctification, on the other hand, is the process of being made holy, which follows justification and is also a work of God's grace.

Implications for Christian Living:
While salvation is not earned by works, the New Testament teaches that genuine faith will produce good works as evidence of a transformed life. James 2:17 states, "So too, faith by itself, if it does not result in action, is dead." Thus, while works are not the basis of salvation, they are the fruit of a living faith.

Conclusion:
The doctrine of salvation by grace through faith is central to the Christian gospel, emphasizing the sufficiency of Christ's work and the necessity of faith. It assures believers of their secure standing before God, not based on their own righteousness, but on the righteousness of Christ imputed to them through faith.