Why do we say salvation is not by works?

The assertion that salvation is not by works stems from a fundamental understanding of grace. Ephesians 2:8-9 clarifies that it is by grace that we are saved, through faith, and this is not of ourselves; it is a gift of God. This means that human actions or merits cannot contribute to salvation because it detracts from the completeness of Christ's atonement. Salvation is solely an act of God's mercy, demonstrating His power and grace. To claim otherwise is to undermine the sufficiency of Christ's work on the cross.