Galatians 3:12

Not of faith. The law does not operate on the basis of faith; it does not require faith on the part of those who practice it.

The man that doeth. This is a quotation from Lev. 18:5. Paul now appeals to the law itself to prove to his Judaizing opponents that what he teaches concerning the law is simply an affirmation of what the law says of itself. The law demanded rigid compliance with all its requirements, but provided no means whereby men could comply. Law does not and cannot enable the sinner to attain to the standard of righteousness that it exalts. In fact, all men are sinners (Rom. 3:10, 23), including those who have sought to acquire righteousness through the legal system (v. 9). All that is prescribed by the law is works, but works of law are worthless in making a sinner righteous before God. This righteous status can be attained only through faith in the covenant promises (Gal. 3:6, 14).

Live in them. That is, live a righteous life, or be accepted in God’s sight as righteous. The facts were, however, that all who had ever sought perfection through the law alone had fallen short of the goal and thereby brought upon themselves “the curse” (see on v. 10).