What does the Bible say about legalism and grace?

Legalism posits that one can earn God’s favor through adherence to the law, thereby undermining the sufficiency of Christ's work. In Galatians, Paul confronts this error, stating that if salvation is by grace, it cannot include works; otherwise, grace is no longer grace. The belief that one can be justified by the law is fundamentally flawed because it implies that Christ's death was not sufficient for salvation. Paul draws a line against legalism, emphasizing that our assurance must rest only on Christ and his grace, not on our performance or adherence to the law.