Deuteronomy 1-6

The introduction to Deuteronomy in my New American Bible (New Catholic Translation) explains that Deuteronomy is "a partial repetition, completion and explanation" of the law given by the Lord at Mt. Sinai. As I read the first six chapters, a number of the themes that permeated the first four books of the Pentateuch jump out.  

First, fruitfulness:

The Lord, our God, has so multiplied you that you are now as numerous as the stars in the sky. May the Lord, the God of your fathers, increase you a thousand times over, and bless you as He promised!

Second, trust in the Lord:

Do not fear or lose heart.

. . . and again

Fear [your enemies] not, for the Lord, your God, will fight for you.

Third, God's tender caring and the Israelites' lack of trust:

The Lord, your God, who goes before you, will himself fight for you, just as he took your part before your very eyes in Egypt, as well as in the desert, where you saw how the Lord, your God, carried you as a man carries his child, all along your journey until you arrived at this place. Despite this, you would not trust the Lord, your God.

Fourth, the Israelites are a special people, and a light to the nations:

Observe [the Lord's commands] carefully, for thus will you give evidence of your wisdom and intelligence for the nations, who will hear of all these statutes and say, "This great nation is truly a wise and intelligent people."

Fifth, that there is only one god, the Lord our God, who is a jealous God:

For the Lord, your God, is a consuming fire, a jealous God . . . . This is why you must now know, and fix in your heart, that the Lord is God in the heavens above and on the earth below, and that there is no other.

Having sounded these themes, Moses discusses again the Ten Commandments, and focuses especially on the greatest commandment:

The Lord is our God, the Lord alone! Therefore, you shall love the Lord, our God, with all your heart, and with all your soul, and with all your strength.

The Lord asks of me only that I believe this and embrace this; that I trust in Him; that I hear His commands and follow them; and that I not "put Him to the test."  Why is this so hard for me?