What is legalism and why is it a problem for Christians?

Legalism is a misunderstanding of the relationship between the law and the gospel, where individuals believe they can attain righteousness through their efforts to obey the law. This mindset is problematic because it undermines the sufficiency of Christ’s sacrifice and the grace He extends to us. Paul asserts that if righteousness could come by the law, then Christ died in vain (Galatians 2:21). True faith leads us to rest in Christ's work rather than our own, freeing us from the bondage of legalism.