Why do Christians believe in justification by faith?

Justification by faith is central to the gospel message and is articulated in Galatians 2:16, stating that 'a man is not justified by the works of the law, but by the faith of Jesus Christ.' This doctrine emphasizes that no amount of personal merit can achieve righteousness before God; rather, it is through faith in Christ's completed work that believers are declared righteous. This is foundational because it assures believers that their status before God is secure, not reliant on ever-changing circumstances or performances. Furthermore, it fosters a spirit of gratitude and humility, recognizing that salvation is a gift of grace and not a result of human effort.