The Catechism in Questions & Answers

274. How is the Mosaic Law assessed from the perspective of the gospel?

From the perspective of the gospel, the Mosaic Law is not the way to salvation, but it points to the way that leads to salvation: Jesus Christ.
No one can keep the whole of the law. For this reason it is not possible to attain salvation through one’s own endeavour alone. The individual must come to the conclusion: “I am a sinner and need forgiveness of sins.” However, forgiveness of sins requires belief in Jesus Christ.

Salvation, attaining salvation: see Questions 243., 248. et seq.