Leviticus 18:5

5. If a man do, he shall live This important sentence contains the whole doctrine of justification by works. It is rendered more correctly and more emphatically in Ezekiel 20:11; Ezekiel 20:13; Ezekiel 20:21, “he shall even live.” “The precepts of the law,” says Aquinas, “are not concerning things to be believed, but concerning things to be done.” Nevertheless, acceptable doing implies faith, while evangelical believing includes the subsequent doing of the will of God as the fruit of faith. As regards the life here promised, the Jewish interpreters themselves included in it more than mere earthly felicity in Canaan, (Deuteronomy 30:20,) and extended their view to a better life hereafter. The Palestine Targum renders it, “he shall live in them in the life of eternity;” that of Onkelos, “an everlasting life.” Says Tholuck, “ Life seems to be a general promise, and length of days a particular species of felicity. In the New Testament this idea (of life) is always exalted into that of life blessed and eternal. See Matthew 7:14; Matthew 18:8-9; Luke 10:28.” Hence this is a plain intimation of the doctrine of a future life in the Pentateuch, which is denied by some superficial readers. St. Paul found “to be unto death” “the commandment which was ordained to life,” just as the murderer on the scaffold finds that the law against murder, designed to protect life, when transgressed, is “unto death.” The design and normal tendency of the law is life; but through man’s imperfection and disobedience the actual result is death. See Galatians 3:21, note, and John 11:25, note.

In them He shall live in the strength of, or by means of, these laws, in the faithful keeping of which is his fountain of life. But “he is a debtor to do the whole law.” Failure to do this renders “all the world guilty before God.”