Could a person be saved by keeping the law perfectly?
No, a person cannot be saved by keeping the law perfectly, because no man can keep it in its entirety. Although perfect law-keeping would make one righteous enough for Heaven, Scripture concludes all are under sin, so salvation comes by faith in Jesus Christ, not by works of the law.
Les explains from Ephesians 2 that if someone could keep the law in its entirety, they would be righteous enough to be in God's Heaven, but no man can do it. He points to verse 22, where Scripture hath concluded all, both Jew and Gentile, under sin, so that the promise by faith of Jesus Christ might be given to them that believe. Les emphasizes that faith is believing, and the two words are synonymous. Before faith came, we were kept under the law, but salvation has always been by faith, all the way back to Adam.