31:6 — “Be strong and of good courage, do not fear nor be afraid of them; for the Lord your God, He is the One who goes with you. He will not leave you nor forsake you.”
Could anything feel more disconcerting or frightening than having to face a terrible trial all by yourself? God tells us that those who know Him never have to worry about that. He’s right there with us, in the easiest and most difficult of times.
6. Be strong and of good courage. After he had shewn that God would be with them, for their help, he exhorts the people to firmness and magnanimity. And surely this is one means of confirming our courage, to be assured that the assistance which God promises will suffice for us: so far is it from being the case, that our zeal and energy in acting aright is impaired, by our ascribing to the grace of God what foolish men attribute to their own free will. For those who are aroused to strenuous action in reliance on their own strength, do no more than cast themselves headlong in their senseless temerity and pride. Let us understand, then, that all exhortations are fleeting and ineffective, which are founded on anything else but simple confidence in the grace of God. Thus Moses assumes, as his ground of exhortation, that God will fight for the Israelites. It must, however, be observed that the people were animated to the perseverance of hope, when God declares that He will be their helper even to the end, by which lesson that impious hallucination is refuted, whereby the Popish theologians have fascinated the world. They deny that believers can be certain of God’s grace, except as to their present state. Thus do they hold faith in suspense, so that we may only believe for a day, and even from moment to moment, whilst we are in uncertainty as to what God will do with us on the morrow. Whereas, if faith corresponds with God’s promises, and is, as it were, in harmony with them, it must needs extend itself to our whole life, nay, even beyond death itself; for God removes all doubt as to the future by these words, “I will not leave thee nor forsake thee.”
6 In the language of Holy War, Joshua is commanded to “Be strong and courageous. Do not fear … for YHWH is your God; he is going with you” (cf. also v 7 below). See the discussion above for 1:21 and Excursus: “Holy War as Celebrated Event in Ancient Israel.” The promise that God will be with someone is a familiar one throughout the Bible, as witnessed by the meaning of the name Immanuel (“God is with us”) in Matt 1:23 (quoting Isa 7:14; cf. Gen 21:22; 26:3, 28; 28:15, 20; 39:2–3; Exod 3:12; Josh 1:5–9; Judg 6:12–13; Isa 8:10; Jer 1:19).
 Stanley, C. F. (2005). The Charles F. Stanley life principles Bible: New King James Version (Dt 31:6). Nashville, TN: Nelson Bibles.
 Calvin, J., & Bingham, C. W. (2010). Commentaries on the Four Last Books of Moses Arranged in the Form of a Harmony (Vol. 4, p. 314). Bellingham, WA: Logos Bible Software.