John Calvin Commentary Deuteronomy 31:6

"Be strong and of good courage, fear not, nor be affrighted at them: for Jehovah thy God, he it is that doth go with thee; he will not fail thee, nor forsake thee." — Deuteronomy 31:6 (ASV)

Be strong and of good courage. After he had shown that God would be with them to help them, he exhorts the people to firmness and magnanimity. And surely, this is one way to confirm our courage: to be assured that the assistance God promises will be enough for us. It is far from true that our zeal and energy in acting rightly are impaired when we attribute to God's grace what foolish men attribute to their own free will.

For those who are stirred to strenuous action relying on their own strength do nothing more than cast themselves headlong in their senseless recklessness and pride. Let us understand, then, that all exhortations are fleeting and ineffective if they are founded on anything other than simple confidence in God's grace.

Thus, Moses assumes as his basis for exhortation that God will fight for the Israelites. However, it must be observed that the people were encouraged to persevere in hope when God declares that He will be their helper even to the end.

This lesson refutes that impious delusion by which the Popish theologians have captivated the world. They deny that believers²³³ can be certain of God’s grace, except concerning their present state.

Thus, they hold faith in suspense, so that we may only believe for a day, and even from moment to moment, while we are uncertain about what God will do with us tomorrow. However, if faith corresponds with God’s promises and is, so to speak, in harmony with them, it must necessarily extend itself to our whole life, and indeed, even beyond death itself.

For God removes all doubt about the future with these words, I will not leave thee nor forsake thee.

²³³ The dogmatical statement of this error is made in the decrees of the Council of Trent, Sessio vi. vi. cap. Ix, “Contra inanem haereticorum fiduciam.” It is controverted by Ix, “Contra inanem haereticorum fiduciam.” It is controverted by C., Instit. Book iii. ch. ii. Section 40; in his “Antidote to the Council of Trent;” ., Instit. Book iii. ch. ii. Section 40; in his “Antidote to the Council of Trent;” C. . Soc. Edit., p. 125, and elsewhere.p. 125, and elsewhere.