John Calvin on Deuteronomy 30:15-18

15. See, I have set before thee this day. A solemn injunction, similar to the foregoing ones, that the Israelites should consider how inestimable a blessing it was that God should have condescended to deposit His Law with them; and that if they did not receive it with reverence, the punishments for such foul ingratitude would be by no means light. For, in order to deprive them of the pretext of error, He separates them from the heathen nations, which through ignorance of the right way vacillated, as in uncertainty, between life and death. He says, therefore, that He has set before their eyes life, and that indeed connected with true and complete happiness; and likewise death with its consequences. Now, there is no one who, under the guidance of nature, would not seek for life and recoil from death; and thence Moses reproaches them with being more than senseless if they should plunge voluntarily into all miseries. Meanwhile, he signifies that he is not addressing to them mere idle menaces, but that his doctrine is armed with the power of God, so that whosoever should embrace it would find salvation in it, whilst none would despise it with impunity. The distribution of the two clauses then follows, viz., that the love of God and the keeping of His Law is prescribed that they may live; but if they turn away from it, their destruction is denounced. It is not, then, without reason that I have called the promises and threats the Sanctions of the Law, because, in order that its authority may be assured to us, it is necessary that both the recompence of obedience, and also the punishment of transgression, should be set before us. By the worship of other gods, he means every revolt from God, as I have observed already. He does not speak of their being “drawn away” to superstition as an excuse for their instability, but rather as an aggravation of their crime, inasmuch as they are carried away by their depraved desires, Addition in Fr., “comme d’un tourbillon;” as by a whirlpool. and thus desert the truth of God when well acquainted with it.