Why does the Law condemn everyone?
The Law condemns everyone because every human being other than Christ has already broken it, and it requires perfect doing, not merely hearing. It demands that its adherents do what God commanded, so no one can be justified by the Law; all are condemned.
Les explains that the Law condemns everybody because every human being who has ever lived, except Christ Himself, has already broken the Law, and so they are condemned. The Law does not excuse a person merely for not being under Israel; those who have sinned in the Law will be judged by the Law. Verse 13 says the hearers of the Law are not justified before God, but the doers of the Law shall be justified—and Les notes this is under the Law. At Sinai the people answered together, “All that the Lord hath spoken we will do,” which is legalism. The Law demanded doing on the part of its adherents, though it had to be prompted by faith. So the Jew under the Law could not get by with faith plus nothing; he had to have faith plus doing whatever the Law demanded.