Nehemiah 9:29 And testifiedst against them, that thou mightest bring them unto thy law; yet they dealt proudly, and hearkened not unto thy commandments, but sinned thy judgments, (which if a man do, he shall live in them;) and withdrew the shoulder, and hardened their neck, and would not hear.
After the Jews returned to Jerusalem and rebuilt the wall, the Levites are recounting in proclaimed prayer the history of God’s grace and of the people’s rebellion. In this context they retell the period of the Judges as an example of the pattern: they disobeyed the Law and bad things happened, then they repented and good things happened when the Lord delivered them from their enemies.
This is the cause and effect of the conditional promises. The Lord judged them through their enemies to bring them back to the Torah, but when they were proud, disobedient and sinful the Lord separated from them and withdrew, turning a cold shoulder. Many times this cycle recurred: sin – judgment – repentance – deliverance.
Embedded within this rehearsal of salvation history is this parenthesis; “If a person keeps the Law he will live.” This is a fundamental Biblical conditional promise, and it scares the bejesus out of us. We should be terrified because we know we have not kept the Law; therefore we are not alive but dead in sin. The horror of judgment disappears when we hear the words of Romans 1:17, “The just shall live by faith.” The words by faith changes everything. Faith in Christ is eternal life. The Gospel proclaims: the “if” condition of righteous law-keeping has been satisfied by Jesus, and by faith in Him you have too. By faith you kept the Law; by faith you are alive in Christ; by faith YOU LIVE! The Law promises life if you keep it, but it brings death if you don’t. The Gospel gives life when you believe it, but leaves you in death if you don’t.